In the 1970s, there was an oversupply of college graduates  The excessive supply reduced the average annual income of college graduates to a level that was only 18% higher than that of workers with only high school diplomas
By the 1980s, the average annual income of college graduates was 43% higher than that of workers with only high school diplomas, although the supply of college graduates did not decline from the 1970s to the late 1980s
The economy has slowed down, thereby reducing the demand for college students.