Data Insights
Bite-sized insights on how the world is changing, published every few days.
June 13, 2024
Solar panel prices have fallen by around 20% every time global capacity doubled
One of the most transformative changes in technology over the last few decades has been the massive drop in the cost of clean energy. Solar photovoltaic costs have fallen by 90% in the last decade, onshore wind by 70%, and batteries by more than 90%.
These technologies have followed a “learning curve” called Wright’s Law. This states that the cost of technology falls consistently as the cumulative production of that technology increases.
The chart shows the perfect example of this for solar power. This data comes from the International Renewable Agency, Greg Nemet, and Doyne Farmer & François Lafond.
On the horizontal axis, we have the cumulative installed capacity of solar panels, and on the vertical axis, the cost. Both are measured on logarithmic scales, and the trend follows a straight line. That means the fall in cost has been exponential.
Costs have fallen by around 20% every time the global cumulative capacity doubles. Over four decades, solar power has transformed from one of the most expensive electricity sources to the cheapest in many countries.
Learning curves: What does it mean for a technology to follow Wright’s Law?
Technologies that follow Wright’s Law get cheaper at a consistent rate, as the cumulative production of that technology increases.
June 12, 2024
The price of lighting has dropped over 99.9% since 1700
In the last two centuries, the price of lighting has decreased drastically.
You can see this in the chart, which plots historical data from Roger Fouquet and Peter Pearson. To allow for comparisons over time, the data is adjusted for inflation and expressed in prices for the year 2000.
In the 1300s, one million lumen-hours — a standard lighting measure — would have cost around £40,800 in 2000 prices. By 2006, this had fallen to £2.90, a 14,000-fold decline.
Innovations in lighting appliances, fuels, infrastructures, and institutions during the 19th and 20th centuries made this progress possible.
To put this in perspective, consider that a standard 100-watt incandescent light bulb today can emit about 1,700 lumens. Therefore, running one such bulb for 24 hours would produce about 50,000 lumen-hours. That means that 1 million lumen-hours today would require continuously keeping a standard 100-watt incandescent bulb on for about 25 days. Achieving the same amount of light with candles would require burning more than 100 candles every day for that period.
Most people today take the ability to switch on a light at night for granted. But those who live or have lived without artificial light can appreciate how important it is.
June 11, 2024
Homicide rates have declined dramatically over the centuries
It is hard to imagine just how violent the past was.
The chart shows that in the 13th and 14th centuries, based on data from researcher Manuel Eisner, homicide rates across Western Europe were higher than 10 murders per 100,000 people in a year. In Italy, the rate was as high as 70 murders per 100,000 people.
Since then, murder rates have fallen significantly across these countries. According to data from WHO’s Mortality Database, their homicide rate is now around 1 murder per 100,000 people — less than a tenth of what it used to be.
Despite these improvements, homicides remain a common cause of death globally and are even a leading cause in some countries. But significant and lasting reductions in violence between people are possible.
June 10, 2024
Which countries have fertility rates above or below the “replacement level”?
Fertility rates — which measure the average number of children per woman — have been falling worldwide. Since 1950, global fertility rates have halved, from almost 5 children per woman to 2.3.
As a result, global population growth has slowed dramatically, and many countries' populations are expected to decline by the end of the century.
This is because fertility rates in many countries have fallen below the “replacement level”. This is the level at which a population replaces itself from one generation to the next. It’s generally defined as a rate of 2.1 children per woman.
The map shows which countries had fertility rates above and below this level in 2021. This is based on estimates from the UN World Population Prospects.
June 07, 2024
Core LGBT+ rights are becoming more protected in some countries
Important LGBT+ rights are becoming better protected in some countries, according to the work of researcher Kristopher Velasco.
The chart shows that in the early 1990s, very few countries protected LGBT+ rights beyond allowing same-sex sexual acts. Back then, no countries allowed same-sex partners to marry or adopt children, none recognized a third gender, and only two made it easy to change one’s gender marker legally.
Over the last few decades, more countries have offered and protected these rights. Most countries have now legalized same-sex relationships, and same-sex marriage, adoption, third-gender recognition, and gender marker changes are becoming more common. However, most countries still do not recognize these important rights.
June 06, 2024
Many countries are “leapfrogging” landlines and going straight to mobile phones
The concept of “leapfrogging” is popular in development. It suggests that lower-income countries can, as they develop, skip intermediate technologies or systems to go straight to the modern equivalent.
One example of this is the use of landlines and mobile phones.
The landline telephone was invented in 1876 and became a dominant form of communication across Europe and North America. As you can see in the chart, it was increasingly adopted in the United States and the United Kingdom throughout the 20th century.
However, mobile phone adoption increased rapidly in the 1990s, and landlines have declined since the millennium. Mobile phones have become a substitute for landlines.
Many countries, however, have almost skipped the adoption of landlines entirely. India, Ghana, and Nigeria are good examples: landline subscriptions have remained extremely low, and instead, mobile phone adoption has exploded.
June 05, 2024
Deaths from tetanus have been reduced massively
Tetanus is a bacterial disease that causes paralysis and can lead to death.
Globally, it was estimated to kill more than 250,000 people each year in the early 1990s. Most of these deaths were in children.
By 2019, annual deaths had fallen to less than 35,000.
The rollout of the combined vaccine against diphtheria, tetanus, and pertussis (DTP) among children has been crucial in driving this.
June 04, 2024
Mobile money accounts are surging globally, especially in Africa and Asia
Mobile phones and the Internet have enabled the growth of mobile money accounts in regions with limited banking infrastructure. These accounts provide simple financial services like deposits, transfers, and payments to hundreds of millions of people.
As this chart shows, the number of active mobile money accounts globally has grown from 13 million in 2010 to more than 640 million in 2023. This is based on data published by the GSM Association.
While the adoption of mobile banking was almost exclusive to Sub-Saharan Africa in the early 2010s, Asian countries have seen significant growth in recent years.
June 03, 2024
There are large differences in LGBT+ rights across the world
As shown on his map — based on an index calculated by researcher Kristopher Velasco — LGBT+ rights vary greatly between countries.
The index combines information on 18 policies, including same-sex relationships, marriage, and gender markers. Higher values indicate more and better-protected rights; negative values represent regressive policies.
In some countries, people can legally be in same-sex relationships, get married, and adopt children. But in many others, LGBT+ rights are poorly protected, or policies are regressive. Some countries explicitly ban same-sex marriage or impose severe punishments, including the death penalty, for same-sex relationships.
While some countries have made progress in protecting LGBT+ rights, most still have a long way to go to achieve equality.
Explore differences in LGBT+ rights across countries and over time →
May 31, 2024
More than 80 billion land animals are slaughtered for meat every year
According to the Food and Agriculture Organization of the United Nations, the number of land animals slaughtered for meat production has risen continuously for the past 60 years.
In 2022, the reported total reached 83 billion worldwide.
This number does not include additional deaths that occur during the production of meat and dairy, such as male baby chickens slaughtered in the egg industry, and other animals for which no data exists.
As the chart shows, the immense majority of these animals are chickens. Ducks and pigs are the second and third species most frequently slaughtered.
How many animals get slaughtered every day?
Hundreds of millions of animals get killed for meat every day.
May 30, 2024
Winters have warmed faster than summers in the United States
The world is getting hotter as a result of climate change, with some countries warming faster than others. But within countries, warming is not equal across the year.
In the United States, winters have warmed faster than any other season. This is followed by spring, with summer and fall showing the slowest rates.
The chart below shows the temperature anomaly — the change in seasonal temperature compared to the average over the 20th century (1901 to 2000). This data is collected and published by the National Oceanic and Atmospheric Administration.
American winters have warmed by nearly 3 degrees Fahrenheit (°F), compared to 1.5°F to 2°F in other seasons.
Minimum temperatures have increased faster than maximum temperatures. That means nighttime temperatures have increased more than daytime temperatures.
May 29, 2024
Airline hijackings, once relatively common, are rare today
Airline hijackings are often considered a very visible and prominent form of modern terrorism, with the 9/11 attacks in the United States in 2001 being a well-known tragic example.
Historical data from the Aviation Safety Network shows that airline hijackings have a long history but have become much less frequent than in the past.
Between 1968 and 1972, hijackings reached a peak, with over 305 incidents recorded globally within those five years.
In 2021, the most recent year with available data, there were 3 incidents, none involving fatalities.
May 28, 2024
On average, people have lived much longer than the period life expectancy at their time of birth
The data on this chart comes from the Human Mortality Database.
It shows that in 1930, people in France had a period life expectancy of 57 years. Period life expectancy is a metric that summarizes age-specific mortality rates in one particular year. This means that newborns would live 57 years on average if they experienced the same death rates at each age of their lives as those seen at each age in the population that year.
However, these newborns actually faced lower death rates than previous generations and lived an average of 69 years. This second measure — the average lifespan of a birth cohort — is called cohort life expectancy. It can only be calculated once all cohort members have died.
Period life expectancy is the more commonly reported “life expectancy” measure. However, these two measures are very different, and the gap can be large, as this data shows.
Read more on the difference between period and cohort measures →
May 27, 2024
One in five democracies is eroding
Based on the Episodes of Regime Transformation data, this chart shows that around 20% of democracies were slowly deteriorating in 2023.
According to the underlying expert assessments by country experts, elections are becoming less meaningful, free, or fair in these countries.
This rate of democratic erosion is unprecedented.
This is partly because the data seeks to capture gradual declines in democratic institutions, while historically, democracies often broke down rapidly in coups d’état or foreign invasions.
So, while political rights are under threat in a substantial share of democracies, there is still time to act to halt this decline, restore democratic rights, and even deepen democratic institutions.
If you want to learn more, you can read my article on recent changes in democracy, for which we just updated the data.
May 24, 2024
There are huge inequalities in global CO2 emissions
Richer people tend to have a higher carbon footprint. They consume more energy, and since much of it still comes from fossil fuels, they have much higher carbon emissions than those on lower incomes.
This inequality is clear when we examine countries' contributions by income level. The chart above shows the four World Bank income groups’ share of global carbon dioxide (CO2) emissions and population, using data from the Global Carbon Project. The groups are based on the average income at the country level — they don’t account for differences between people’s incomes within each country.
High-income countries contribute more than twice their share of the global population: they are home to just 15% of people but emit 34% of global emissions. Low-income countries are home to 9% of the global population but emit less than 1% of total emissions.
This gap increases by several percentage points when we account for emissions embedded in traded goods.
May 23, 2024
In less than a decade, Peru has become the world's second-largest blueberry producer
Between 2012 and 2022, Peru's blueberry production went from less than a thousand tonnes to nearly 300,000 tonnes per year.
According to estimates from the UN Food and Agriculture Organization, this huge growth in output was enabled by a rapid expansion in the land used to grow blueberries, together with substantial gains in the number of tonnes produced per cultivated hectare.
These trends show that significant agricultural changes can happen very quickly.
Explore the world's food system crop-by-crop from production to plate →
May 22, 2024
Much more progress can be made against child mortality
The world has made great progress against child mortality. But in many countries, a significant share still die during childhood.
The data on this map comes from the UN IGME, which estimates child mortality rates worldwide using detailed household surveys and vital statistics.
As the map shows, child mortality is much lower in rich countries, where fewer than 1% of children die before the age of five.
However, the figures are much higher in poor countries, especially across Africa and South Asia. In Pakistan, for example, 6% die before their fifth birthday. In Nigeria and Somalia, the figure is 11%.
These statistics show that despite impressive falls in child mortality, much more progress can be made.
Child mortality: an everyday tragedy of enormous scale that we can make progress against
We live in a world in which ten children die every minute.
May 21, 2024
The price of computer storage has fallen exponentially since the 1950s
This chart shows the dramatic fall in the price of computer storage between 1956 and 2023. It relies on the data carefully collected by the computer scientist John C. McCallum.
In the last 70 years, the price for a unit of storage has fallen by almost ten orders of magnitude. The data is plotted on a logarithmic scale on the vertical axis. The line follows an almost straight path, indicating an exponential reduction in price.
A 256-gigabyte storage capacity — commonly found in standard laptops sold today — would have cost around 20 billion dollars in the 1950s. (That’s in today’s prices.)
And cost has not been the only improvement: modern solid-state drives offer much faster and more reliable data access than early magnetic and hard disk drives.
Read more on the exponential growth of computing capabilities →
May 20, 2024
In the last 200 years, many countries have built institutions to collect statistics on their populations
Governments need accurate information about their populations to implement effective policies.
But historically, few countries collected basic statistics on their people, so they knew little about them.
The chart here shows that, over time, many countries have built such institutions.
Starting in the 19th century, they began conducting population censuses, creating civil registers, and establishing statistical agencies. In the later 20th century, they started setting up population registers and using register-based censuses.
Thanks to these efforts, these countries better understand where people live, what jobs they have, who was born, and who has died.
However, many countries still lack these institutions, which makes it challenging for them to direct projects and policies where they are most helpful.
May 17, 2024
More than 30 countries have legalized same-sex marriage
The Netherlands was the first country to legalize same-sex marriage in 2001. Since then, more than 30 other countries have followed suit.
You can see this in the chart, based on data from Pew Research. By 2022, same-sex marriage was legal in 32 countries.
Since then, 3 more countries have joined this group: Andorra, Estonia, and Greece — bringing the total to 35. Last year, Nepal also registered its first same-sex wedding, but it’s not yet clear whether these rights are available across the country.