I found these statistics on reading (thanks to Ron and Andrea, and O'DonnellWeb), which came from a larger group of stats found here, at ParaPublishing.
If these are accurate, then:
58% of the US adult population never reads another book after high school.
42% of college graduates never read another book.
80% of US families did not buy or read a book last year.
70% of US adults have not been in a bookstore in the last five years.