WASHINGTON (AP) — Fixed mortgage rates were mostly unchanged this week, inching up from their yearly lows.

The average rate on the 30-year fixed loan ticked up to 4.52 percent from 4.51 percent a week ago, Freddie Mac said Thursday. It reached its yearly low of 4.49 percent a month ago.

The average rate on the 15-year fixed loan, popular for refinancing, nudged up to 3.66 percent from 3.65 percent, its low point for the year.

Mortgage rates typically track the yield on the 10-year Treasury note. Yields fall when prices rise. In the past week, yields have been stable even though Congress and the Obama administration are less than two weeks away from a possible default on the government's debt.

Negotiations to raise the government's $14.3 trillion borrowing limit have yet to produce a deal that can pass both chambers of Congress, although a bipartisan Senate plan has drawn support from President Obama.

Low mortgage rates and depressed home prices have done little to revive the struggling housing market. Many people simply can't take advantage of the historically low rates because of tighter lending standards and bigger required down payments.

Other potential homebuyers are holding off, concerned that housing prices will continue to fall.

Few economists expect the housing market to rebound before 2013.

To calculate average mortgage rates, Freddie Mac collects rates from lenders across the country on Monday through Wednesday of each week. Rates often fluctuate significantly, even within a single day.

The average rate on a five-year adjustable-rate mortgage edged down to 3.27 percent from 3.29 percent last week. Three weeks ago, it hit 3.25 percent, its lowest level on records dating back to 2005. The average rate on the one-year adjustable loan rose to 2.97 percent from 2.95 percent. It hit a record low last week.

The rates do not include extra fees known as points. One point is equal to 1 percent of the total loan amount.

The average fees for the 30-year loans were unchanged at 0.7, according to Freddie Mac's survey. Average fees for the 15-year fixed loan rose to 0.7. Fees for the five-year and one-year ARMs were 0.5.