Rental vacancy rates for the nation fell from 8.4% in 2009 to 7.4% in 2011, according to data released by the U.S. Census Bureau.

According to the data, four times as many metros saw falling rental vacancy rates when compared to those experiencing increases.

The number of U.S. households that rent rather than own a home rose from 34.1% in 2009 to 35.4% in 2011. Nearly 25% of the nation’s metros saw a rise in renting households, while less than 3% saw a drop.

The study revealed that more renters are spending a high percentage of their income on rent. In this report, renters spending 35% or more of household income on rent and utilities are considered to have high rental costs. 

The number of renters with high housing costs in the U.S. increased from 42.5% in 2009 to 44.3% in 2011. However, average rental rates in the U.S. declined during the same time period.

"While we saw a decrease in rental vacancy rates and pricing in some areas, the burden of rental costs on households increased across many parts of the nation," said Arthur Cresce, assistant division chief for housing characteristics at the Census Bureau. 

He added, "Factors such as supply and demand for rental housing and local economic conditions play an important role in helping to explain these relationships."