In its latest mobile app report, comScore tracks the 25 most popular apps in the US. This is an interesting slice of the App Store, as it highlights active usage, not just one-time downloads or recent popularity. Some observations: Facebook is by far the top app, with 115.4 million unique visitors in June. With 160 million total US app users, that’s 72% penetration—pretty impressive. (For context, Facebook said it had 1.1 billion mobile users ...