Americans have a lot going on. Netflix shows to watch. Facebook feeds to scroll through. And surprisingly, these leisure activities might be a reason Americans are having less sex, according to a new study published in Archives of Sexual Behavior.

The study compared data from the late '90s to data from the early 2010s. Researchers found American adults had sex nine fewer times per year in 2014 than they did in the late '90s. For married couples who live together, frequency was even lower. In 1989, married couples had sex 67 times per year. In 2014, it was down to 56 times per year.

The study cites a few reasons why this could be the case. Americans now have a variety of other activities at their fingertips, such as streaming services like Netflix, social media and smartphone games. "There are now so many other ways to spend leisure time at home," psychology professor Jean Twenge, the study's lead author, told TIME.

In fact, those who were raised with easy access to screentime reported the lowest numbers of sexual frequency. The study found millennials and Generation Z are having less sex than previous generations. Perhaps these generations find the lure of technology and entertainment more appealing than older generations, which leads to less frequent sex.

On the other end of the spectrum is the most active generation: people over 70. "They had sex nearly 11 times during 2014, up from an average of 9.6 times in 1989," the New York Times reported.

Maximizing relationship happiness

For couples looking to optimize their happiness, TIME cites another study that found the ideal number of times to have sex per week. This study was published in Social Psychological and Personality Science.

According to the study, couples who have sex once per week reap the most happiness benefits. More frequent sex did not increase happiness. But couples who had sex less than once per week reported being less happy. Lead researcher Amy Muise told TIME more frequent sex wasn't a problem. Those couples just didn't see higher happiness returns in their relationship.