SAN FRANCISCO - JULY 08:  A sign advertising an apartment for rent is displayed in a window July 8, 2009 in San Francisco, California. As the economy continues to falter, vacancy rates for U.S. apartments have spiked to a twenty two year high of 7.5 percent, just short of the record high of 7.8 percent set in 1986. (Photo by Justin Sullivan/Getty Images)