Here is there list of the top five:
1. The Hunger Games by Suzanne Collins
2. Catching Fire by Suzanne Collins
3. Mockingjay by Suzanne Collins
4. Fifty Shades of Grey by E.L. James
5. Harry Potter and the Sorcerer’s Stone by J.K. Rowling
On the “Stories” area of their website they offer an Infographic of the the list.