From the Washington Post:

Now, a pretty dramatic new report out from Piper Jaffray — an investment bank with a sizable research arm — rules that the kids are over Facebook once and for all, having fled Mark Zuckerberg's parent-flooded shores for the more forgiving embraces of Twitter and Instagram. Between fall 2014 and spring 2014, when Piper Jaffray last conducted this survey, Facebook use among teenagers aged 13 to 19 plummeted from 72 percent to 45 percent. In other words, less than half of the teenagers surveyed said "yes" when asked if they use Facebook. (A note: There's no spring data available for the "no networks" option, which is why that spot is blank.)