I can tell you that it's always difficult to talk about prevalence because, depending on what you're trying to target, you can come up with different numbers. If you talk about the prevalence of inmates upon admission who have any mental disorder, including substance abuse disorder, you're looking at 75% to 80%. If you are looking at a much more narrow definition, people who have what was previously known as axis I disorders—people who basically are disconnected with reality and may be suffering from schizophrenia, major depression or things of that nature—you're looking at 7% to 8%.
I think the best prevalence data that I use is this: Upon admission, how many people need psychological or psychiatric services? That number is about 29%, which is way off the charts compared with the general Canadian population.