“Currently, 40 percent of all first-time freshmen begin their postsecondary
careers in community colleges, the great majority of them intending eventually to complete a bachelor’s degree. But along the way something
happens, and for most of them that ambition is thwarted. The question is,
to what extent does this pattern reflect students’ choices, and to what extent is it
due to factors beyond their control?”

http://www.carnegiefoundation.org/dynamic/publications/elibrary_pdf_721.pdf