USA Today reports that 1 in 9 housing units in the US are vacant.

“The numbers are further documentation of the gravity of the housing problem,” says Nicolas Retsinas, head of Harvard University’s Joint Center for Housing Studies. “This inventory is delaying any kind of housing recovery.”

Adding vacation homes drives the number to about 15%, compared to 11% and 9.4% during the recessions of 1991 and 1984, respectively.