That’s according to a new report from the Pew Research Center, in which researchers studied census data going back more than 130 years concerning the living arrangements of young adults.

According to the report, in 2014, 32.1% of young adults lived in their parent(s) home, with 31.6% of those aged 18 to 34 living with a partner or spouse. 14% lived alone, while 22% had some other living arrangement, such as living with extended family members a sibling, or in group housing.

“This turn of events is fueled primarily by the dramatic drop in the share of young Americans who are choosing to settle down romantically before age 35,” the report reads. “Dating back to 1880, the most common living arrangement among young adults has been living with a romantic partner . . . this type of arrangement peaked around 1960, when 62% of the nation’s 18-34 year olds were living with a spouse or partner in their own household, and only one-in-five were living with their parents.”

As you can see, the all-time high rate of young adults living with their parents actually peaked way back in 1940, but at that time there was still a higher rate of young adults living with a partner or spouse. This is one reason why Pew researchers named changing attitudes towards marriage and monogamy as a prime driver for changes in living arrangements. Pew points out that the median age of first marriage has been rising steadily for decades, and estimates that one-in-four of today’s young adults will never marry at all.

At the same time, it’s difficult to separate social factors, like attitudes toward romantic commitment, from economic ones. The report points out that “Employed young men are much less likely to live at home than young men without jobs,” and that “the share of young men with jobs peaked around 1960 at 84%.” That’s the same year that the share of young adults living on their own peaked, which suggests that plentiful jobs lead to plentiful marriages and newly formed households.

The trend that Pew identifies is one likely reason that the homebuilding market has yet to recover, even a decade after the peak of the real estate bubble. Despite the fact that home prices have recovered to their pre bubble trend, the number of new homes being built today remains far below the highs in previous expansions, due to a combination of rising costs for home builders as well as muted demand from young Americans declining to form households until later in life.