Housing affordability continues to hover near a 10-year low, and the National Association of Home Builders is urging policymakers to do something about it.

Of the new and existing homes sold in the fourth quarter of 2018, just 56.6% were affordable for those earning the country’s median income of $71,900, according to the NAHB/Wells Fargo Housing Opportunity Index.

This is up just barely from the previous quarter, as a slight increase in interest rates offset a small decline in home prices, the report stated.

The national median home price was $263,000 in Q4, down from $268,000 in Q3.

But at the same time, the average mortgage rate is increasing, up 17 basis points to 4.89% in Q4 from 4.72% in Q3. This marks the fourth-straight quarter of rate hikes and is the highest level since 2011, the report noted.

NAHB Chairman Randy Noel housing is an early indicator of overall economic health, urging officials to take action.

"Builders are finding it increasingly difficult to build at price points most consumers need because they are struggling with burdensome regulations, higher material costs and shortages of lots and labor," said Noel. "Historically, housing has been the canary in the coal mine, and these ongoing affordability woes should serve as a wake-up call to policymakers to take immediate action."

NAHB Chief Economist Robert Dietz said home price appreciation has outperformed wage growth, and that is stifling housing affordability.

"To keep housing moving forward, policymakers at all levels of government should make it a priority to address affordability concerns that are hurting homebuyers and home builders alike," Dietz said.

The report also highlighted the most and least affordable markets across the country.

Youngstown-Warren-Boardman, Ohio-Pennsylvania, was the most affordable major housing market, with 92.7% of homes sold in Q4 affordable for those earning the area's median income of $60,100.

For the fifth-straight quarter, San Francisco was the nation's least affordable major market, with just 6% of the homes sold in Q4 affordable for those earning the area's median income of $116,400.