According to a new poll from Trades Union Congress (TUC) and women’s equality group Everyday Sexism, more than half working women in Britain say they have experienced some form of sexual harassment. That number is even higher—63%—for young women, age 18 to 24. And perhaps even more disturbing: Four out of five of these women say they did not report the behavior to their employer.

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The TUC surveyed 1,533 U.K. women, aged 18 to 65. They found that the most commonly reported instances of harassment include overhearing colleagues making comments of a sexual nature about another woman or women (35%) and unwelcome jokes of a sexual nature (32%). Twenty-eight percent of respondents say they’ve dealt with personal comments of a sexual nature about their own bodies or clothing. Nearly 25% say they’ve experienced unwanted touching, and about one fifth have been the victim of unwanted sexual advances.

At the most serious end of the spectrum, one out of ten women said she had experienced unwanted attempts at kissing or groping, which, according to the TUC, could be defined as sexual assault under UK law.

In 54% of cases the women say the harasser was a colleague. Seventeen percent report that the perpetrator was their direct manager or someone else in the company with power over them.

The vast majority of respondents said they did not report the incident or incidents to their employers. Just 6% said they did report—and that the situation was “taken seriously and dealt with satisfactorily.” (Seven percent said they reported the behavior but were unhappy with how it was handled.)

Women who opted not to tell their employer what happened were most likely to say that they thought speaking up would damage their work relationships (28%) or that they wouldn’t be believed or taken seriously (24%).

Not surprisingly, many of the women who report being harassed say the experience had harmful after-effects. Poll respondents were mostly likely to say that the harassment embarrassed them, caused them to avoid some work situations, or undermined their confidence at work.

“Employers need to do much more—it is clearly a huge problem,” said Everyday Sexism founder Laura Bates, in an interview with Reuters UK. “The first step is taking it seriously … so people know that harassment won’t be tolerated.”

Everyday Sexism encouraged women to share their own stories of harassment using the hashtag #HarassedAtWork. Here’s just a sampling of how Twitter users responded:

https://twitter.com/Joelle_o/status/763343977001148416

#harassedatwork cornered by 2 old men aggressively discussing how much better I looked after losing weight & that I was "showing off"+

— Darleeeeeene (@spaceytracy91) August 10, 2016

@EverydaySexism bending to get floor cleaner, "joked" at by boss standing at sink, "while you're down there…" #harassedatwork

— Dr Nicola Monster (@NicolaMoffat) August 10, 2016

https://twitter.com/LorrieHartshorn/status/763282442656645120