The number of underwater homeowners in the Washington area decreased again in the last quarter of 2012, continuing a trend that has brought relief to thousands of borrowers.

In the Washington region, the percentage of homeowners who owe more on their mortgage than their homes are worth dropped to 28 percent in the fourth quarter of 2012, compared with 32 percent during the same period a year ago, according to a report by Zillow, which tracks real estate data. That means that rising home prices freed more than 45,000 homeowners from negative equity in the Washington area last year.

That is about the same as borrowers are seeing on a national level. At the national level, the percentage of underwater homeowners fell to 27.5 percent of homeowners with a mortgage in the fourth quarter, from 31.1 percent at the end of 2011.

Graphic: Delinquent mortgages in the Washington area

Economic data has painted a resilient picture of the housing market as home prices rose at rates last seen before the financial crisis and new home sales surged. The increasing popularity of short sales also made it easier for struggling homeowners to let go of distressed property.

Zillow predicts that almost 1 million more homeowners will be freed from underwater mortgages by the end of 2013, pushing the negative equity rate for the country down to 25.5 percent. (The figure is calculated based on anticipated changes in home values.)

Zillow expects another 25,000 borrowers to be freed from underwater mortgages this year in the Washington region.

“As home values continue to rise and more homeowners are pulled out of negative equity in 2013, the positive effects on the housing market will be numerous,” Zillow’s chief economist Stan Humphries said in a statement.

Despite this progress, many borrowers are still in trouble. With an underwater mortgage, borrowers can’t refinance and have a harder time selling their home. More than 300,000 homeowners, or about 18 percent of borrowers, are still underwater in the Washington region.

And there is still a big disparity in underwater mortgage rates throughout the region.

More than half of borrowers are underwater on their mortgage in Prince George’s County, nearly 90,000 homes. This is a big improvement from the fourth quarter of 2011 when it was 60.2 percent. Charles County’s percentage of negative equity is 51.5 percent, from 53.8 percent in 2011. The percentage of underwater homes in Virginia’s Prince William County is 30.9 percent (down from 38.5 percent a year ago).

But that stands in stark contrast to Fairfax County where only 14.9 percent of borrowers are underwater. That is down from 18.4 percent during the fourth quarter of 2011. The rate for Montgomery County is 21.4 percent, compared with 23.9 percent a year ago.