Improving economies often bring with it a lack of interest in higher education while a slowing economies often push people to return to school. According to the National Student Clearinghouse Research Center enrollments in 4 year for-profit institutions declined 13.7%, 2 year public institutions 2.4% and 4 year non-profit .03%. Enrollments for 4 year public rose 2.3%.
Total decline for all higher education institutions was approximately 2.3%
When the economy improves people don't feel as though their jobs are under threat and naturally they don't rush to turn that bachelor's degree into an MBA. Alternatively, when the economy turns sour people become more insecure in their employment and feel they must compete.
This is the problem with the higher education market. People get secure and are not motivated and when times get tough they want to adapt and brush up on their skills. Education is seen as very practical in the sense that a new degree leads to higher pay and performance. A one to one relationship occurs in people's minds.
There maybe something else going on as well. People are seeking alternative forms of education. Certificates, MOOCs, seminars, and personal study may be popular options to going back. Students may be seeking alternative forms of education and could be turned off by the cost propositions. Millennials seem to avoid high debt and traditional ways of doing things.