Compiling data on economic inequality from countries all around the world is a hefty task, which has been shouldered by a group of more than 100 researchers around the world who contribute to the efforts of the World Inequality Lab and the World Wealth and Income Database. The World Inequality Report 2018, written and coordinated by Facundo Alvaredo, Lucas Chancel, Thomas Piketty, Emmanuel Saez, Gabriel Zucman, provides an overview of their findings. Here are a few of the figures that jumped out at me.
This figure shows the share of income going to the top 10% of the income distribution in a number in some prominent countries and regions. Inequality in the US-Canada area (blue line) is clearly rising, but so is inquality across all of these areas. In particular, economic development in China and India has made some parts of those economies much better-off than others, so inequality his on the rise. The rise of inequality in Russia during the 1990s is also apparent.
This is a similar graph, but with a different set of comparison regions. The blue line for the US-Canada area remains the same. But as you can see, inequality in the Middle East, sub-Saharan Africa, and Brazil have long been above US-Canada levels, and by this measure, India has now passed the US level of inequality.
For example, the figure shows that an adult who was in the 20th percentile of the world income distribution in 2016 had an income that was about 120% higher than an adult who was in the 20th percentile of the world income distribution in 1980. The "head" of the elephant shows that the gains to those in the 20-40th percentiles of the world income distribution were substantial. The drop in the middle shows that gains were smaller for those from the 50th-80th percentiles of the world income distribution. And on the far right, the top percentile is divided up into smaller slices. The gains for the top percentile were substantial, but comparable to those in the 20th-40th percentile. However, the gains the top 0.01% and the 0.001% were substantially larger. Of course, these groups at the very top are also for much smaller groups, and thus are harder to measure, and probably also involve more turnover year-to-year.