"The ability value (intelligence, knowledge and the intelligent use of knowledge) of the smart fraction (95th percentile, comparable to an IQ 125 or higher in within-country norms) is more important for country differences in wealth, nations’ intellectual excellence (in STEM fields: patents, Nobel Prices in science, scientists, high technology exports) and political attributes of societies (government effectiveness, democracy, rule of law and political liberty) than the average ability or the ability level of a non-smart fraction (5th percentile, comparable to an IQ 75 or lower in within-country norms). But the cognitive ability level of the non-smart fraction is more important for country differences in HIV, AIDS and homicide. Wealth differences between countries could be completely explained through differences in high intellectual achievement in STEM fields, which itself largely depends on differences in smart fractions ability. The smart fraction is essentially relevant for beneficial societal development."
H. Rindermann et al., The impact of smart fractions, cognitive ability of politicians and average competence of peoples on social development, 2009