Housing affordability nationwide during the fourth quarter 2010 rose to its highest level in the 20 years since it has been measured, according to the National Association of Home Builders (NAHB)/Wells Fargo Housing Opportunity Index (HOI).

Nearly three-quarters (73.9 percent) of all new and existing homes sold in the fourth quarter were affordable to families earning the national median income of $64,400, according to the report. This is the eighth consecutive quarter the index has been more than 70 percent. Before 2009, the HOI rarely topped 65 percent and never reached 70 percent.

"Today’s report shows that housing affordability at the end of 2010 was at its highest level since we started computing the HOI," said Bob Nielsen, chairman of the NAHB. "However, while this is good news for consumers, both homebuyers and builders continue to confront extremely tight credit conditions, and this remains a significant obstacle to many potential home sales."