If you already have an mobile app or are in the process of developing one, here are 3 reasons to start doing App Store Opmization NOW: 1. App Store & Google Play include 775,000 apps each already! 2. 81 % of U.K. App Store visitors stop browsing after checking out the top 50 apps. 3. 75 % of users download apps from the top charts without having heard about them before.