As a decade-long economic boom pushes into 2020, affording a home isn't expected to become much easier for the average American, according to recent reports.

Average wage earners can't afford to buy a home in 344 of 486 counties, or 71% of the U.S., according to a fourth-quarter analysis from real estate research firm Attom Data Solutions. That's just a slight improvement from from 73% in the third quarter and 75% a year earlier, the Attom report found.

One reason for the glacial pace of improvement? A booming real estate market amid lower mortgage rates.

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Home prices rose 9% year-over-year in the last three months of 2019, making the "typical home" a "financial stretch for average wage earners," Todd Teta, chief product officer with Attom, said in the report.

To cross the current national median home price of $257,000, homebuyers need a gross income of $67,647, the report said — yet the average annual wage in the U.S. was $58,214, the report notes.

That can be punishing math for the typical homebuyer.

(Speaking of math: Attom determined housing affordability by calculating the amount of income needed to make monthly house payments — mortgage, property taxes and insurance — on a median-priced home, assuming a 3% down payment and a 28% debt-to-income ratio. Income was compared to annualized average weekly wage data from the U.S. Bureau of Labor Statistics.)

Home prices to climb in 2020

Though homes are "actually a bit more affordable" in recent months, prices are expected to keep climbing "in the near-term," Teta noted.

Attom isn't alone in its prediction. Another analysis from real estate site Zillow predicts home values will rise about 2.2% in 2020.

One reason for the tightening market: "underbuilding" of new housing stock because of higher labor and land costs, according to a statement from the National Association of Home Builders.

That's even as real estate markets continue to improve across the country and confidence in most U.S. markets remains at 20-year highs, Robert Dietz, the NAHB's chief economist, said in the statement.

A steady drop in the 30-year mortgage rate to about 3.8% last month from 4.9% just a year ago is stoking demand, helped by a cut in lending rates thoughout 2019 by the Federal Reserve to sidestep the threats of a potential recession stemming from a slumping global economy and the uncertainties surrounding President Donald Trump's trade war with China.

Lower lending rates mean it's less expensive to finance a 30-year mortgage. Lower financing costs can make it easier for buyers to swallow higher hime prices.

Sales of newly built homes rose 1.3% in November, a sign that lower mortgage rates this year are helping push purchases and prices higher. Sales of existing homes dropped 1.7% last month, considered a sign of shrinking supply, not shrinking demand. Combined, the figures signal there aren't enough homes on the market at prices low enough to meet burgeoning demand.

Rents are rising, too

The largely unaffordable state of home sales is seen as one reason the number of people renting climbed at double the rate of those buying homes in the decade since the housing collapse and Great Recession, up 9.1% compared to 4.3%, according to a recent analysis from RentCafe.

Some 34% of Americans — or more than 100 million people — are renting, the largest chunk of the U.S. population since the 1960s, RentCafe found. Yet renting isn't getting any cheaper, either.

The national rent average rose to $1,473, up $390, or 36%, in the past 10 years, RentCafe found. That's faster than the rise in median income, up 27% in the past decade.

And the nation's homeless population is also rising, up 2.7%, the Associated Press recently reported, citing an annual count from January 2019 by the U.S. Department of Housing and Urban Development. It's the third consecutive rise in HUD's homeless projection for the U.S., driven largely by housing conditions in California, the AP noted.

—The Associated Press contributed to this report.