The average conforming 30-year fixed mortgage fell again this week, to 5.15 percent according to Bankrate.com's weekly national survey. The average 30-year fixed mortgage has an average of 0.45 discount and origination points.

The average 15-year fixed mortgage dropped to 4.56 percent while the larger jumbo 30-year fixed rate retreated to 5.93 percent. Adjustable rate mortgages were lower as well, with the average 1-year ARM dipping to 4.92 percent and the 5-year ARM sliding to 4.63 percent.

Disappointments on the corporate earnings front helped bring mortgage rates lower for a third straight week. Mortgage rates are closely related to yields on long-term government and mortgage-backed bonds. On larger jumbo mortgages, the average 30-year fixed rate is at the lowest level since June 2005. Although the margin between rates on jumbo mortgages and smaller conforming loans has narrowed further in recent weeks, it is still nearly one-half percentage point above normal, pre-credit crisis levels.

The last time mortgage rates were above 6 percent was Nov. 2008. At that time, the average rate was 6.33 percent, meaning a $200,000 loan would have carried a monthly payment of $1,241.86. With the average rate now 5.15 percent, the monthly payment for the same size loan would be $1,092.05, a savings of nearly $150 per month for a homeowner refinancing now.

SURVEY RESULTS

30-year fixed: 5.15% - down from 5.23% last week (avg. points: 0.45)

15-year fixed: 4.56% - down from 4.62% last week (avg. points: 0.42)

5/1 ARM: 4.63% - down from 4.68% last week (avg. points: 0.37)