A follow-up if you don't mind.

I have a friend who did some time a decade or so ago (I'm uncertain if it was a federal or state prison) and one thing I've noted about him is how much he values books, even stuff like manuals and outdated reference material (we're in a volunteer group and we were cleaning up a room with a bunch of trash). His explanation to me was that in prison there wasn't much to do and so he spent his time reading as much stuff as he could get his hands on.

From your experience, would you say that the average rate of reading amongst inmates is higher than the general population? In person I've hardly met anyone who reads books other than for school assignments.