Extreme poverty has not declined in these four Southern African countries

Depression, anxiety, and other mental health problems are common everywhere. They are not confined to any particular income level.

But access to care is rare. In much of the world, people who struggle with their mental health have almost no psychologists or psychiatrists to turn to.

Mental health care is scarce in all places, but it is much scarcer in poor countries. Governments in high-income countries spend about $66 per person per year on mental health care, as the chart shows. In low-income countries, that figure is $0.04.

This gap in spending reflects a gap in people. As the WHO’s latest Mental Health Atlas highlights, there is roughly one psychiatrist per million people in low-income countries. High-income countries have 70 times more.

A recent study in the Lancet Psychiatry estimated that globally, only 9% of people with major depressive disorder receive a “minimally adequate treatment”. In high-income countries, it is 27%; in Sub-Saharan Africa, just 2%.

Hundreds of millions of people in poorer countries live with treatable conditions and have no access to a psychologist or psychiatrist. It is one of the largest gaps in global health — and one that receives remarkably little attention or funding.

There are efforts to close this gap without waiting for the workforce to catch up. One approach is to train lay counsellors — people without formal clinical qualifications who learn to provide psychological support. Randomized trials in India and Zimbabwe have shown this can be effective for depression.

Another approach is to use technology: apps and, increasingly, AI-based tools that can extend the reach of limited clinical expertise. These are not substitutes for a functioning mental health system, but in places where that system barely exists, they offer a starting point.

There are two ways to produce seafood: catch fish in the wild or farm your own. Seafood farming is often called “aquaculture”. Aquaculture is dominated by the farming of fish, but also includes other organisms, such as crustaceans and aquatic plants.

Aquaculture has grown rapidly over the last few decades. In fact, as the chart shows, it has overtaken wild catch since 2013.

This has relieved some pressure on wild fish stocks: if this increased demand for fish had been satisfied by wild catch, then many more would be severely overexploited.

Last year, three-quarters of the world’s countries had unemployment rates below 10%, according to data from the International Labour Organization. Colombia, where I come from, is in that group.

I initially found Colombia’s relatively low unemployment rate surprising, because it didn’t match what I could see around me: many people doing extremely precarious work.

This chart offers an explanation. It shows, for a selection of countries of different income levels, what share of workers hold informal jobs, meaning work that lacks social protection and basic employment rights (no guaranteed benefits, no formal safety net).

As the chart shows, in Colombia, that share is almost 57%. In many lower-income countries, the share is far higher.

The reality is that low unemployment and widespread informal work can, and often do, happen at the same time. The reason this isn't paradoxical comes down to how these statistics are defined.

To count as employed in labor statistics, a person only needs to have worked for at least one hour during the survey’s reference period, often the past week. The definition is broad and includes self-employment, selling things on the street, and unpaid work in a family farm or family business. Both formal and informal jobs are included.

This means the unemployment rate can remain relatively low in poor countries, not because most workers have found stable, protected jobs, but because many have been absorbed into informal employment.

The United Kingdom was the birthplace of coal. It has now, effectively, died there.

As shown in the chart, in the late 1980s, around two-thirds of the UK’s electricity came from coal. By the time I was born in the 1990s, this had dropped to just over half.

The use of coal has plummeted in my lifetime. It now makes up around 0.1% of the UK’s electricity.

Coal was first replaced by gas, but is now being pushed out by wind, solar, and biomass.

In a recent Data Insight, I wrote about how Argentina was one of the richest countries in the world at the beginning of the 20th century. Today, I want to follow up with a striking comparison between Spain and Argentina.

The chart shows GDP per capita for Argentina and Spain over the last two centuries. These are historical estimates from the Maddison Project, and the data is adjusted for inflation and differences in the cost of living.

When Argentina declared independence from Spain in 1816, the two countries had very similar GDP per capita. By the late 19th century, Argentina had become richer than its former colonial power, and it stayed ahead for many decades. Spain then started growing faster in the 1960s, and by the mid-1970s it had caught up.

Continued economic growth in Spain after the 1980s drove the large gap we see today. It kept GDP per capita on a steep upward path into the 21st century. Argentina, by contrast, grew more slowly and went through several economic crises, visible on the chart.

Today, Argentina’s GDP per capita is closer to my home country of Colombia than to Western European countries like Spain. This helps us see how much of a difference economic growth can make within just a few generations.

Forty years ago, young people had higher literacy rates in Sub-Saharan Africa than in South Asia. You can see on the chart that the region had a 10-percentage-point lead in 1985.

But things have changed a lot since then. Sub-Saharan Africa now lags by more than 14 percentage points.

While literacy has improved in both regions, it has done so much faster in South Asia. There, almost all young people have basic reading and writing skills. In Sub-Saharan Africa, most of them do, but there is still a significant lag behind other world regions.

In South Asia, the increase in literacy rates among young women has been particularly dramatic. In the mid-1980s, only around 40% had basic reading skills. That has more than doubled to over 90%, and the gap between young men and women has essentially closed.

When I first visited Buenos Aires some years ago, I was struck by how grand the city's historic architecture was. This is something that strikes many tourists: parts of the city feel closer to Paris than you’d expect from a country whose income level today is more similar to my home country of Colombia than to France.

This chart helps put that observation in perspective. It shows the ten richest countries in the world in 1910, according to GDP per capita estimates from economic historians.

By this measure, Argentina was among the world’s richest countries in 1910, ahead of several Western European countries, including Germany and France. It also stood clearly ahead of its peers in Latin America at the time.

But over the course of the 20th century, Western European economies grew far faster, especially after the Second World War, and Argentina fell behind.

A long-run perspective like this shows how much of a difference economic growth can make within just a few generations.