NEW YORK CITY — Reports of sex crimes in the subway are up 52 percent over a three year period, but arrests have lagged, according to a report published Tuesday that advocates for tougher sentences for subway gropers.

There were 941 reports of sex crimes on subways in 2016, which included 454 cases of forcible touching, 126 sex abuse cases and 286 cases of public lewdness, according to the report pieced together from NYPD data published by Staten Island State Senator Diane Savino.

Arrests were made in 491 or about a half of those cases in 2016, the report found.

In 2014, after the MTA created a website making it easier to report subway crimes, there were 620 reports of sexual harassment and 65 percent of those incidents resulted in arrest, the data shows.

That shows a 13 point decrease in the ratio of crimes to arrests.

Many of those arrested were repeat offenders. Last year, about a third of the people arrested for sex crimes had already been arrested for sex crimes in the past.

Savino is pushing the State Assembly to pass legislation she's repeatedly introduced and passed in the Senate that would make forcible touching a class D felony instead of misdemeanor and would thus increase the maximum prison time a person could serve to 7 years if convicted instead of one year.