In the 2002 book IQ and the Wealth of Nations, and IQ and Global Inequality in 2006, Richard Lynn and Tatu Vanhanen created estimates of average IQs for 113 nations.
A 2007 meta-analysis by Rindermann found many of the same groupings and correlations found by Lynn and Vanhanen, with the lowest scores in sub-Saharan Africa, and a correlation of .60 between cognitive skill and GDP per capita.