The U.S. 30-year fixed-rate mortgage rate dropped slightly to 3.99 percent in the week ending Nov. 10, according to Freddie Mac's Primary Mortgage Market Survey.

The 30-year mortgage rate fell slightly from 4 percent in the previous week, and was also below the 4.17 percent rate in the same period in 2010.

It was the second time this year that the 30-year mortgage rate dropped below 4 percent. In the week of Oct. 6, the mortgage reaced 3.94 percent, a record low.

The average 15-year mortgage fell to 3.30 percent, down from 3.31 percent in the previous week and 3.57 percent at the same time last year.

Fixed mortgage rates were little changed this week amid a mix of economic data reports. The economy added 80,000 net jobs in October, below the market consensus forecast, but employment gains over the prior two months were revised up by 102,000 and the unemployment rate fell to 9.0 percent, the lowest in six months, said Frank Nothaft, vice president and chief economist of Freddie Mac, in a statement.

The drop in interest rates coincided with continued declines in home prices. Earlier this week, the National Association of Realtors reported that home prices dropped in 74 percent of major U.S. metro areas during the third quarter.

Soft house prices and low mortgage rates have kept home-buyer affordability historically high, said Nothaft.

Although the low interest rates allowed some homeowners to reduce their debt through refinances, as Freddie reported, tighter lending standards have made it more difficult for new homebuyers to secure mortgages. Continued economic uncertainty have led many Americans to rent instead of buy, and some real estate commentators believe that a full housing recovery won't occur until 2013.