After 15 months of dominating the social network's statistics, Zynga's FarmVille is no longer the most popular application on Facebook as ranked by monthly users, unseated by an innocuous app called Phrases. FarmVille has held the top spot on the site since August 2009 and reached its peak of 84 million monthly active users earlier this year. In March, Facebook implemented changes to its notification system in an effort to reduce spam, and many of its top social games have shed millions of users since. This includes FarmVille, which currently has 53.9 million monthly players and continues to lose users each week. It remains the most popular social game on Facebook, though, and its daily active audience of 16 million players is still bigger than that for any other app -- its closest competition is Windows Live Messenger with 9.7 million daily users. Developed by Takeoff Monkey, Phrases enables people to post sayings, images, and quizzes from a variety of pre-generated topics on their newsfeed. It's managed to grow virally to 54.3 million monthly users by attaching links to itself on newsfeed posts, and by enabling users to create and share quizzes with other Facebook users. Phrases isn't expected to stay at the top of Facebook's statistics for long, as Takeoff Monkey recently disabled the app for U.S. users without offering any explanation. The app's daily active count is dropping fast, according to Inside Facebook, and it could quickly drop to #2 or even further if this restriction remains. Despite the slight setback for FarmVille, Zynga still operates five of the top seven most popular apps on Facebook: including Texas HoldEm Poker, FrontierVille, Mafia Wars, and Cafe World. The developer is also planning its first international game launch, CityVille, with a public beta in the coming weeks.