Given that Facebook boasts 1.8 billion monthly active users users, and there are about 3.5 billion Internet users, it seems broadly plausible that 80% of people

Given that Facebook boasts 1.8 billion monthly active users users, and there are about 3.5 billion Internet users, it seems broadly plausible that 80% of people on the Internet have used Facebook — but 80% definitely aren't regular users.