What is the correlation between intelligence and income? Razib Khan, Gene Expression, used the GSS’s WORDSUM variable to indicate intelligence, which has a ~0.70 correlation with IQ. He used REALINC for income, which is indexed to 1986 values (so it is inflation adjusted) and aggregates the household income. and then Razib limited his sample to non-Hispanic whites over the age of 30 ( this also limited the data set to respondents from the year 2000 and later).
Ten out of 10 on WORDSUM does not imply that you’re that smart really. But the trendline is suggestive. Note that aggregated 0-4 because the sample size at the lower values is small indeed.