Video site YouTube is the most popular online platform among teenagers, displacing Facebook, which once dominated social media with that age group.

That is according to a new study from Pew Research Center.

Only about half (51%) of teens 13-17 said they use Facebook, compared with 85% who said they use YouTube. In fact, Facebook is also topped by Instagram (72%) and Snapchat (69%). Rounding out the top five was Twitter, with 32%.

Asked which platform they use most often, respondents again gave YouTube the win, with 32% saying it is their go-to site, followed by Instagram at 15%. With 10%, Facebook again placed fourth.

Facebook has been under pressure in Washington and elsewhere to clean up its algorithmic and user privacy act in the face of questionable user-data sharing, Russian election hacking, fake news, allegations of conservative bias and more.

The social media site dominated in Pew's last survey of teens' online usage, conducted in 2014-2015, with 71% of teens saying they used the site, compared with 52% who used Instagram and only 41% who used Snapchat. But a big caveat is that YouTube was not included as an option in that 2014-2015 survey.

Another difference is that in the 2014-2015 survey, respondents had to give an explicit response to whether they used each platform, while the new survey gave them a list of sites and let them pick the ones they use.

Nonetheless, Pew said, "it is clear the social media environment today revolves less around a single platform than it did three years ago."

Almost 95% of teens have access to a smartphone, the survey found, while 45% said they were online "almost constantly."

On the gaming front, 97% of boys said they played video games online, compared with 83% of girls.

The online/phone study was conducted among 743 teens and has a margin of error of plus or minus five percentage points.