Top 5 Best Sellers of the Decade

The top 3 spots go to E L James' "50 Shades of Grey" series. The trilogy sold nearly 35 million copies. Fourth place goes to Suzanne Collins' "The Hunger Games". "The Help" by Kathryn Sockett rounds out the list.

Other trends for the decade: Paper books outsold e-books; 6.5 billion to 1.8 billion copies. Audio books continue to rise in popularity due to mobile devices.

In 2010, fiction took 80% share of top sellers. Today, fiction makes up 32% of best selling titles. Shorter books, including self-help and poetry have become more popular.