By ALEX VEIGALOS ANGELES (AP) â¿¿ A resurgent housing market, rising home values and steady job gains are helping more U.S. homeowners stay on top of their mortgage payments. The percentage of mortgage holders at least two months behind on their payments fell by 21 percent in the first three months of this year versus the same period in 2012, credit reporting agency TransUnion said Wednesday. The sharp annual decline in the mortgage delinquency rate represents the biggest quarterly drop on record for TransUnion, whose data go back to 1992. "We certainly expected improvement this quarter, as the housing sector is in recovery, but the magnitude of the improvement was unexpected," Tim Martin, TransUnion's group vice president of U.S. housing, said in a statement. All told, the mortgage delinquency rate was 4.56 percent in the first quarter. That's down from 5.78 percent in the prior-year quarter, TransUnion said. The first-quarter rate also fell 12 percent compared with the last three months of 2012, when it was 5.19 percent, a four-year low. Even so, the mortgage delinquency rate is still above the 1 percent to 2 percent average historical range, an indication that many homeowners still are struggling to make their payments. Before the housing bust, mortgage delinquencies were running at less than 2 percent nationally. They peaked at nearly 7 percent in the fourth quarter of 2009. The rate has been trending down since then, aided by a rebound in home sales and rising home prices that began gaining traction about a year ago. U.S. home prices rose 10.5 percent in March compared to a year earlier, the biggest gain since March 2006, according to real estate data provider CoreLogic. March marked the 13th month in a row that home prices have increased on an annual basis nationwide. Rising home values make it easier for borrowers to refinance their mortgages or sell their homes if they lose their jobs or otherwise become unable to make payments. They also help bring down the number of homeowners who are underwater on their mortgage, or owe more on their home loan than their homes are worth.