Facebook "only" 31 billion (but with Instagram & Messenger the company has 4 of the top 10 apps in "time spent globally"). Clash of Clans 3.8 billion, Fortnite 3 billion. WTF??? We might be underestimating what humanity does - living in front of screens.
Research/study by Apptopia: https://blog.apptopia.com/these-are-the-apps-taking-up-most-of-your-time
Good article with more details on Forbes: