Over 32 percent of American adults ages 18-34 are living with their parents, making this the leading living arrangement for this group, according to a Pew Research Center report.

Since 1880, the earliest date for which statistics are available, the primary living arrangement for young adults had been living with a spouse or partner.

Also among this age group today, 31.6 percent lived with a spouse or partner, 22 percent lived with another family member, non-relative or in group quarters such as dormitories, and 14 percent lived alone or as a single parent.

The number of 25- to 29-year-olds living in their parents’ homes rose sharply from 18 percent in 2006 to 25 percent in 2014—among the highest levels on record. Also, 13 percent of 30- to 34-year-olds living with their parents in 2013 and 2014 (up from 9 percent in 2006) was the highest level for that group since 1940, when the nation was still recovering from the Great Depression.

Comparatively, the number of young adults ages 18 to 24 still living at home only slightly increased from 46 percent in 2006 to about half in 2014. This is mostly due to post-secondary schooling normally not finishing until a person’s mid-20s.

“A variety of factors contribute to the long-run increase in the share of young adults living with their parents,” Pew study author Richard Fry stated. “The first is the postponement of, if not retreat from, marriage. The median age of first marriage has risen steadily for decades. In addition, a growing share of young adults may be eschewing marriage altogether.”

In addition, greater unemployment and lower wages have made it more difficult for young adults to afford their own housing. Employment among 18- to 34-year-old men dropped from 84 percent in 1960 to 71 percent in 2014.

In response to the study, Philip Cohen, a sociology professor at the University of Maryland, told The Washington Post, “I see this as part of an overall trend in an increase in family diversity and decline in the nuclear-family household.”