Yes they do. In fact I think that during the last 20 years or so Middle School kids have been reading a lot more and they were reading long before Harry Potter, but Harry helped. I think that one of the reasons why they have been reading more is that more and more very good books are now available to young readers. They are no longer stuck with badly written teenage agnst formula books.
   Also, they are crossing over to adult books at a younger age than ever before and are becoming very sophisticated consumers of literature. The observation that they don't read as much is often made by people who do not speak to young people on the subject of books.
Of course there are still a lot of kids who do not read, there are no books in their homes, the parents don't read or value reading. But for the most part ,I think we underestimate how much kids do read.