I have understood some drop in fiction book sales to be caused by the wind-up of the Harry Potter series in 2007. A 2011 article from The Guardian (Datablog section, author uncredited) linked to this spreadsheet of Harry Potter book sales numbers: https://docs.google.com/spreadsheets/d/1C6QriM1aMBd5Ab6Tn7hn...

Is Rowling's Potter part of Literary Fiction? The report states "We therefore leave the definition of what literary fiction is, open. [...] What it definitely is not, for our purposes, is poetry or plays. We are looking at fiction." Which causes me to believe it does fall within their definition.