Americans shelled out $20.6 billion more in rent in 2014 compared to 2013. Cumulatively, U.S. renters paid $441 billion in rent in 2014 compared to $420 billion last year, an increase of nearly five percent (4.9 percent), as both the number of renting households and the average rent rose nationally, according to a Zillow rentals analysisi.

Locally, the Bay Area, consisting of the San Jose and San Francisco metros, saw the largest jump in cumulative rent paid in 2014, up 14.4 and 13.5 percent respectively. Rent per household in the San Jose, Calif. metro rose by $197 per month, while rent in the San Francisco metro rose by $163 per month.

Out of the top 50 largest U.S. metro areas, the largest amount of cumulative rent was paid the New York-Northern New Jersey ($50 billion) and Los Angeles ($34 billion) metros. The smallest amount of cumulative rent was paid by renters in Birmingham, Ala. ($1 billion), Louisville, Ky. ($1.2 billion) and Buffalo, N.Y. ($1.2 billion).

Nationally, the total number of renters is estimated to have grown 1.9 percent in 2014ii. Over the same time period, the median rent paid increased 2.9 percent.

"Over the past fourteen years, rents have grown at twice the pace of income due to weak income growth, burgeoning rental demand, and insufficient growth in the supply of rental housing. This has created real opportunities for rental housing owners and investors, but has also been a bitter pill to swallow for tenants, particularly those on an entry-level salary and those would-be buyers struggling to save for a down payment on a home of their own," said Zillow Chief Economist Stan Humphries. "Next year, we expect rents to rise even faster than home values, meaning that another increase in total rent paid similar to that seen this year isn't out of the question. In fact, it's probable."

* Data for the 50 largest metros covered in this Zillow rentals report is available.