WASHINGTON — Rates on 30-year mortgages fell this week to the lowest level in six weeks.

The mortgage company Freddie Mac reported yesterday that 30-year, fixed-rate mortgages averaged 6.22 percent this week compared with 6.30 percent last week.

The decline was only the second since early December. It pushed rates to the lowest level since the 30-year mortgage was at 6.21 percent the week of Jan. 11.

Freddie Mac's survey showed that other types of mortgage rates also fell this week.

Rates on 15-year fixed-rate mortgages, a popular choice for refinancing, were at 5.97 percent, down from 6.03 percent last week. Five-year adjustable-rate mortgages slipped to 5.96 percent from 6.01 percent last week. One-year ARMs dropped to 5.49 percent from 5.52 percent last week.

A year ago, rates on 30-year mortgages stood at 6.26 percent, while 15-year mortgages were at 5.89 percent, five-year adjustable-rate mortgages averaged 5.96 percent and one-year ARMs were at 5.32 percent.