Home prices are rising faster than wages in most of the country, which means the average American is finding it harder to buy a house, particularly in the larger markets, Reuters reported.

The study found that the Des Moines-West Des Moines market is less affordable than it has been, and that wage increases of 3 percent over the past year were outstripped by an 8 percent jump in the median home price.

RealtyTrac said the Des Moines-West Des Moines market had an affordability index of 112; 100 is the norm, and numbers below that mean an area has become more affordable with higher figures meaning less affordability.

RealtyTrac reported that Des Moines-West Des Moines residents spend 21.9 percent of their income on their house, well below many real estate agents' rule of thumb of 30 percent. The first-quarter median price of $145,250 was up 8 percent over the previous year.

The report, based on home sales data and federal wage reports, found that home price growth exceeded wage growth in nearly two-thirds of the nation's housing markets so far this year. Among the least affordable counties were those that include Omaha, St. Louis, Denver, New York City, Dallas and Austin, Texas.

Home prices in 9 percent of the U.S. housing market are now less affordable than their historic norms, the RealtyTrac report found. That means home buyers have less money for other purchases.

"While the vast majority of housing markets are still affordable by their own historic standards, home prices are floating out of reach for average wage earners in a growing number of U.S. housing markets," said Daren Blomquist, senior vice president at RealtyTrac, which monitors housing market trends.

RealtyTrac studied home sales and income data in 456 U.S. counties with a combined population of 221 million.