I recall reading a report that stated the bulk of young-adult readers were adults in their late 30s to their 40s. Which makes sense seeing as reading among youth is down compared to a decade prior and even before. Even with the advent of smart phones and Kindles, they don't read as much. The book buying habits of various demographics are incredibly interesting and so deeply ingrained that they don't change much year over year, even after a decade of ebooks becoming more common. Ignoring the 2000s and the silly Sony reader.