The number of shared households made up 18.7% of all households in the nation in 2010, growing from 17% in spring 2007, according to a U.S. Census Bureau report.

Following the recession, the number of these households increased 11.4% from 2007 to 2010, reaching 22 million people, while total households grew by only 1.3%.

“Although reasons for household sharing are not discernible from the survey, our analysis suggests that adults and families coped with challenging economic circumstances over the course of the recession by joining households or combining households with other individuals or families,” said Laryssa Mykyta, Census Bureau analyst and co-author of the report. 

In 2010, 30.1% of all adults lived in a shared household, up from 27.7% in 2007.

A shared household, in this case, includes an “additional adult” over the age of 18 who isn’t enrolled in school and isn’t the cohabitating partner or spouse of the householder.

More than half of the additional adults were under the age of 35, but since the recession, those in the 25 to 35 age demographic accounted for almost half of the rise in people who live with another householder.

The number of these “adult children” living with their parents grew from 1.2 million to 15.8 million in the three years between 2007 and 2010.

Additional adults showed higher personal poverty rates compared with primary adults in 2007 as well as 2010, following the “understanding of household sharing as a strategy to pool resources.”

“Household sharing seems to be a means of alleviating economic strain at the household level,” the report said.

The report compares data from the Annual Social and Economic Supplement of the Current Population Survey, which monitored household composition in December 2007 prior to the recession and then again in June 2009 after the recession had ended.

For more information, read the full report here.