NEW YORK >> The average rate on the 30-year fixed mortgage fell below 5 percent this week, as investors sought more Treasury notes amid growing tension in the Middle East.

Freddie Mac said today that the average rate on the 30-year loan slipped to 4.95 percent from 5 percent. It hit a 40-year low of 4.17 percent in November.

The average rate on the 15-year fixed home loan fell to 4.22 percent from 4.27 percent. It reached 3.57 percent in November, the lowest level on records dating back to 1991.

Mortgage rates tend to track the yield on the 10-year Treasury note. It fell this week as investors shifted money out of stocks and into safer assets amid escalating violence in Libya.

Even though rates are two-thirds to three-quarters of a percentage point higher than their lows just three months ago, they remain at historically low levels.

Still, rates have done little to boost the housing market. Buyers are reluctant to purchase because of high foreclosures, tight lending standards, job concerns and expectations that home values will continue to fall.

New-home sales tumbled 12.6 percent last month, the Commerce Department said Thursday. Sales of previously owned homes edged up in January, but remained at a weak pace, the National Association of Realtors said Wednesday.

Foreclosures continue to depress the market and weigh on prices. They represented 37 percent of all previously owned home sales in January and all-cash buyers made up nearly a third of those sales, NAR said. First-time homebuyers, who traditionally make up 40 percent of the market, represented only 29 percent of all sales.

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 fell to 3.80 percent from 3.87 percent. The five-year hit 3.25 percent last month, the lowest rate on records dating back to January 2005.

The average rate on one-year adjustable-rate home loans edged up to 3.40 percent from 3.39 percent.

The rates do not include add-on fees, known as points. One point is equal to 1 percent of the total loan amount. The average fee for the 30-year fixed loan, the five-year ARM and the 1-year ARM in Freddie Mac’s survey was 0.6 point. The average fee for the 15-year fixed loan was 0.7 point.