NEW YORK (CBSNewYork) — A lot of women know what it’s like to be harassed on the street, but it may surprise you to find out how young it often starts.

Cornell University and anti-harassment group Hollaback! conducted the largest-ever study on global street harassment.

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Web Extra: Read The Study Here

The study of more than 16, 000 women around the world found that 84% of them say they experienced street harassment before the age of 17, CBS2’s Cindy Hsu reported.

In the U.S., 72 percent of women said they took different transportation due to harassment.

Alexa Briglia told Hsu she’s had men follow her down the street. “It’s so unwanted and it makes me feel really scared,” said Briglia.

“Harassment isn’t just cat calling, it’s also being followed, touched, groped, having people make sexual gestures,” said Debjani Roy of Hollaback!

The survey begain in 2014 and was done in two parts: The first part focused on the U.S. and the second focused on 42 cities worldwide.

Roy said harassment it can cause anxiety, depression and affect self-esteem — especially when it starts young, Hsu reported.

“We have people as young as 7 writing in stories of being harassed … on their way to school,” said Roy.

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Harassment starts at puberty for many girls, said Roy. She said it’s never too soon to talk your children about street harrasment and to teach them how to deal with it safely.

Sometimes that means not responding. But if you do, Roy says to keep it short and succinct.

“Say that’s disrespectful, I don’t appreciate it and keep moving.”

Thousands of people are sharing their stories on the Hollaback! app and website, and the group is mapping every incident with pink dots that shows a story of street harassment, Hsu reported.

“You’ll see when you click on it, it will pop up,” said Roy. “You also have the option in New York City to share it with your local council member and they get all of this information. You want the whole community to get involved.”

Roy is hoping that will turn things around, Hsu reported.

Last August, Shoshana Roberts was the subject of a Hollaback! PSA on catcalling. Wearing jeans and a black T-shirt, Roberts was filmed with a hidden camera and was catcalled more than 100 times over 10 hours while walking the streets of Manhattan.

The video was posted on YouTube, and Roberts later received rape threats over social media.

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Researchers said witnesses often don’t step in to help the person being harassed.