Online Computer Library Center - Stats on collections
"What's the most popularly held book in libraries around the world? Which author or character—or monster or animal—is found most often on library shelves worldwide? The research division of OCLC (the Online Computer Library Center, which libraries in more than 110 countries use to locate and lend library materials) compiled a list of the top 1,000 titles owned by member libraries—the intellectual works judged to be the most worthy based on the "purchase vote" of libraries around the globe."
Quote I like from the site: "What matters, though, is whether your library has the books you consider to be wonderful. And if not, what also matters is whether your library has the support it needs to support your needs."