Facebook is losing young users even faster than expected, according to new estimates from eMarketer.

The digital measurement firm last year predicted that Facebook would see a 3.4 percent drop in users aged 12 to 17 in the US in 2017, the first time it had predicted a drop in usage by any group. old on Facebook.

The reality: The number of US Facebook users in the 12-17 demographic dropped 9.9% in 2017, eMarketer found, or about 1.4 million users in total. That’s nearly three times the expected decline. There were approximately 12.1 million US Facebook users in the 12-17 demographic at the end of the year.

There are likely multiple reasons for the decline. Facebook has been losing its “cool” factor for years, and young people have more options than ever to keep in touch with friends and family. Facebook also serves as a digital registry, but many young people don’t seem to mind saving their lives online, at least not publicly. That explains why Snapchat and Instagram, which offer disappearing photo and video sharing features, are gaining popularity among this demographic.

Overall, eMarketer found that Facebook lost about 2.8 million US users under the age of 25 last year.

And Facebook’s 2018 doesn’t look much better.

The research firm released Facebook usage estimates for 2018 on Monday and expects Facebook to lose about 2.1 million US users under the age of 25 this year.

EMarketer predicts that Facebook will see a decline in usage among all three age groups for people under 25:

A 9.3 percent drop for Facebook users under the age of 11. (Reminder: Facebook’s terms of service require users to be 13 years old to create an account, though it’s easy to avoid.)

A 5.6 percent decrease in users between the ages of 12 and 17.

A decrease of 5.8 percent in users between 18 and 24 years. This is the first time eMarketer has predicted a year-over-year decline in usage for this age group, though it has happened before. In 2016, Facebook’s user base aged 18 to 24 fell 1.5 percent.

Take the numbers with a grain of salt: eMarketer is a third-party research company, so it doesn’t have the full picture that, say, Facebook does.

But the fact that eMarketer predicts declines across the board is a bad sign for Facebook. Young people provide a good barometer of what’s popular, but more importantly for Facebook, losing the next generation of US Internet users is worrying for the company’s long-term dominance.

The good news for Facebook is that despite the expected decline in younger users, eMarketer believes Facebook’s overall US audience will continue to grow over the next few years. More importantly, perhaps, eMarketer expects Facebook-owned Instagram to grow significantly. The research firm believes that Instagram’s US user base will grow 13 percent this year, to nearly 105 million people.

That’s even better than Snapchat’s expected growth: eMarketer believes it will grow its US audience.