https://www.recode.net/2017/8/21/16181348/teenagers-millennials-users-facebook-instagram-snapchat-emarketer

Teens are leaving Facebook faster than expected, according to a new study from research firm eMarketer.

The study estimates that Facebook’s user base among 12- to 17-year-olds in the U.S. will shrink by 3.4 percent in 2017, the first time eMarketer has predicted a decline in Facebook usage for any age group. The company said that it "reduced its usage estimates" for Facebook, but didn’t share what the previous estimates were, and did not immediately reply to a request for clarification.