Why are most Overdrive audio books in WMA format, and not mp3?

My local library allows people to download Overdrive audio books. When I couldn’t find what I wanted on mp3, I was told by the librarian that most of the Overdrive books are in WMA format – but I don’t have a WMA player. I thought that mp3 was a more popular format than WMA. Am [...] http://bit.ly/nOdKP7