I easily read a few a week, depending on the lengths of course!
But then again, I tend to read a lot of young adult novels (which are considerably quicker to get through). If I'm reading manga, I can get through a few a night (because they're obviously less text-based and don't require as much time to read).
I only really read regularly during my lunch breaks at work (and when I can find time at night), but I am trying to reduce the pile of books that I have waiting for me, so that's a good motivation to get through more!