Von Stroh's report found that multifamily buildings with 51 to 99 units had the highest vacancy at 11.1%, little change from the first quarter. Lowest vacancies are in buildings with 200 to 349 units at 9.2%, down from 10.4% in the first quarter. And buildings with 350 or more units had a 10.1% vacancy rate, down a full point from the previous quarter.

"Historically, larger buildings have the highest vacancy rates," Von Stroh notes. This is a sign that owners are doing whatever they can to retain tenants, notes Mark Williams, executive director of the Apartment Association of Metro Denver.

Data from Von Stroh's report further backs that up. Buildings constructed from 1995 to 1999 had a 7.6% vacancy rate, down from 8.7% for the first quarter. And buildings constructed between 1990 and 1994 had a vacancy rate of 6.2%, down from 7.9% in the first quarter. Buildings constructed between 1940 and 1949 had the highest vacancy rate at 15.4%, more than double the 7.2% vacancy rate in the first quarter, a sign that renters are taking advantage of discounts at newer buildings and moving.