Here in 1900 to 1999
https://www.msu.edu/~bsilver/pls440century.html
Education
¶ At the beginning -- and even in the middle -- of the century, high school diplomas were rare, indeed. Back in 1900, for instance, only 6 percent of 17-year-olds graduated from high school. By 1940, 25 percent of people age 25 and over had at least a high school diploma. Today, a diploma is the rule rather than the exception: 83 percent of people age 25 and over had at least a high school diploma in 1998.
¶ The number of degrees conferred by the nation's colleges and universities now is more than 70 times higher than it was at the century's start: fewer than 30,000 were awarded in the 1899-1900 school year, compared with 2.2 mil. in 1995-1996.