Source link for the image: https://brainstats.com/average-iq-by-country.html

" These numbers came from a work carried out from 2002 to 2006 by Richard Lynn, a British Professor of Psychology, and Tatu Vanhanen, a Finnish Professor of Political Science, who conducted IQ studies in more than 80 countries.

Richard and Tatu argues that differences in national income are correlated with differences in the average national intelligence quotient (IQ). They further argue that differences in average national IQs constitute one important factor, but not the only one, contributing to differences in national wealth and rates of economic growth.

These results are controversial and have caused much debate, they must be interpreted with extreme caution. "