Estimates are based on surveys of the non-institutionalized civilian population, so people living in prisons or serving in the military are not included.

The question for education attainment in the Current Population Survey changed in 1992. Before 1992, respondents were asked how many years of schooling they had completed. Starting in 1992, respondents were asked the highest degree they had completed. Those who report having a Bachelor’s, Master’s, Doctorate degree, or Professional degree are coded as having completed four years of college or more.

Time series by race that include data from both before and after 2002 should be interpreted with care. More details on the changes in racial categories.