According to a report by NAHB, the number of “shared households” grew between 2007 and 2010.

In the spring of 2007, 27.7% of adults lived in shared households. By the spring of 2010, that percentage had risen to 30.1%.

Perhaps surprising, the increase in shared households was not concentrated among the youngest of adults. The number of people aged 18 to 24 who were classified as an “additional adult” rose 5.9% over the 2007 through 2010 period. For those aged 25 to 34, the increase was even higher – 18.1%, or 45% of the total increase in shared households. For those aged 35 to 65, there was a still significant 9.7% increase in additional adults.

Those moving in with relatives accounted for 68% of the increase, making moving in with family members the most common occurrence. And adult children moving back in with their parents accounted for 46% of the increase, making that the most common specific event.