Mortgage rates ended their free fall this week, with the 30-year fixed-rate average inching slightly up, according to the latest data released Thursday by Freddie Mac.

The 30-year rose to 3.71 percent from 3.67 percent a week ago, ending the rate’s six-week decline. This time last year, the average was 4.50 percent.

The 15-year average remained below 3 percent, but rose to 2.98 percent from last week’s 2.94 percent. The average was 3.67 a year ago.

For sale signs sit in front of adjacent homes on the market in Alexandria. (SAUL LOEB/AFP/GETTY IMAGES)

Frank Nothaft, Freddie Mac vice president and chief economist, cited the mild week of economic data releases as the reason for the uptick.

“The Federal Reserve Board reported that household net worth rose by $2 trillion to $62.9 trillion over the first three months of 2012 primarily due to increases in stock market,” he said. in a statement. “However, this is still well below the peak of $67.5 trillion set in the third quarter of 2007. Nonetheless, homeowners saw an aggregate $372 billion rise in property values over the first three months of this year.”

Despite the increase, the mortgages rates remain near historic lows , which continues to spur refinancing and home buying.

The Mortgage Bankers Association reported on Wednesday that the number of mortgage applications rose to 18 percent on a seasonally adjusted basis from the previous week, reaching its highest level since May 2009.

On an unadjusted basis, the Market Composite Index, a measure of mortgage loan application volume, soared more than 30 percent compared with the week prior. 

The survey, which covers more than 75 percent of retail residential mortgage applications, found that the Refinance Index increased more than 19 percent from the previous week to the highest level since April 2009. The seasonally adjusted Purchase Index rose more than 23 percent compared with the previous week and was 4 percent higher than the same week a year ago.

“Refinance volume increased as borrowers were able to lock in at mortgage rates below 4 percent, and purchase application volume was its highest level in over six months,” said Michael Fratantoni, MBA’s vice president of research and economics, in a statement.

View Photo Gallery: A selection of homes for sale in the Washington metro area for around $500,000.