 In July 2000, the "Children's Best Sellers" was created after the Harry Potter series had stayed in the top spots on the fiction list for an extended period of time.The children's list was printed monthly until February 13, 2011, when it was changed to once an issue (weekly).In September 2007, the paperback fiction list was divided into "trade" and "mass-market" sections, in order to give more visibility to the trade paperbacks that were more often reviewed by the newspaper itself.