Sex is everywhere. In advertising, in movies, even on smartphones.

Sex can also be beneficial. Many consider it “significant exercise.” It may give you an advantage at work. It has so many positive effects, according to a town official in Sweden, that the official suggested paying municipal workers to go home and do it.

But there is one problem: Americans are having less sex.

That goes for people of all types, regardless of their gender, race, marriage status or the region in which they live, according to a new study published in the journal Archives of Sexual Behavior. In fact, American adults had sex nine fewer times in 2014 than they did in the late 1990s.

From the early 1990s into the early 2000s, Americans generally had sex from about 60 to 65 times a year, according to the study. But after 2002, Americans appeared to lose interest. While the decline has been nearly across the board, one group seems to be pulling everyone else down: married couples.

Married couples generally have sex more often than single people, but that advantage is declining. Married couples had sex an average of 56 times a year in 2014, down from 67 in 1989. But more people are staying single — meaning there is less sex — and the couples who do walk down the aisle are making fewer trips into the bedroom.