Facebook has 2.23 billion monthly active users, which is nearly a third of the world's population. Yet according Marketing Resources Incorporated (MRI), which sifted through insights from mobile app data platform App Annie, it's not the most popular mobile app in any of the 25 developed or populous countries it researched. The messaging app WhatsApp, which is owned by Facebook, actually tops the list in several countries, as does the basketball game Dunk Line. And check out this weirdness: In Germany the two most popular apps are McDonald's apps. Here's an infographic created by MRI which lays it all out, according to country.