[toast0]

Harry Potter was and is super popular. My dinky county library system has 11 physical copies in US english, one in UK english, several non-english languages, and ebooks; our 2010 census county population was only 250k. It's easy to imagine a library that serves a much larger population would need many more copies today, and many more when the book was new, and when the movie was new, and extra copies of the first book when each book and movie came out. Several of my friends would try to read all the existing books timed to finish when a new book was released. Some people would certainly be borrowing those books from the library, especially where people don't have a lot of space for personal libraries.