The coefficient on years of schooling is reported in the top panel of figure 5 for the years of 1977-2004. The return to schooling averages about 9 percent in the late 1970s and the 1980s, and rises to above 10 percent in the early 1990s, before declining back to 9 percent by 2000. There is a change in the coding of the education variable beginning with the 2001 survey, and the reported jump in the return is probably not meaningful. A second formulation used a set of categorical variables to represent the various levels of education, thus dropping the assumption of a linear relationship with years of schooling. The results are reported in the lower panel of figure 5.