Increased demand and a housing shortage in the U.S. continues to make renting a home an expensive proposition for many Americans, according to Zillow's 2017 Consumer Housing Trends Report, set to be released in the fall.

Despite rent growth for houses and apartments slowing over the past year, Zillow found median monthly rent for single-family homes is rising faster than median monthly rent for apartments in half of the 50 largest U.S. metropolitan areas.

Median rent for single-family homes rose 1.3% annually, while median rent for apartments rose 0.5%.

Nearly 20% of single-family homes in the U.S. were rented in 2016, up from 13.5% 10 years ago, according to the report.

Single-family rental homes are in high demand because many aspiring homeowners don't have enough money to buy houses, Zillow said. A 20% down payment on a typical U.S. home costs more than two-thirds of the median household income, and can cost up to 180% of median income in pricier housing markets, like San Jose, Calif., and Los Angeles.

Half of all buyers with children at home considered renting instead of buying, and according to the Census Bureau, 40% of families with children still living at home are renters, Zillow noted.

Renters aged 38 to 52 are more likely to rent a single-family home than any other home type, with over 40% renting single-family homes, compared to 25% of people aged 18 to 37, and just 10% of renters that are 73 years and older, according to Zillow's analysis.