LOS ANGELES, Nov. 3 (UPI) — A poll of men in the United States found fewer of them have paid for or received payment for sex than in decades past.

In several surveys conducted from 1991 to 1996, about 17 percent of respondents said they have either paid for or had received payment for sex at least once in their lives, the Los Angeles Times reported.

Similar surveys conducted between 2006 and 2012 found that number dropped to 13.2 percent.

If fewer men are paying for sex, “it’s because they don’t have to,” said Christine Milrod, an independent researcher and sex therapist from Los Angeles. “They can have sex for free.”

Other researchers said it is possible men are becoming less likely to admit they have paid for sex.

“City after city, state after state, there have been changes in the law that increase penalties for paying for sex,” said Ronald Weitzer, a George Washington University sociology professor. “It might be the growing punitive climate that’s affecting these numbers.”