WASHINGTON — Mortgage rates sank this week, reflecting investors' worries about the country's economic health.

Freddie Mac, the mortgage company, reported yesterday that 30-year fixed-rate mortgages averaged 6.03 percent for the week ending March 6. That was down from last week's 6.24 percent, which had been the highest in three months.

Other mortgage rates also fell this week.

Rates on 15-year fixed-rate mortgages, a popular choice for refinancing, dropped to 5.47 percent this week, from 5.72 percent last week.

For five-year adjustable-rate mortgages, rates fell to 5.34 percent, compared with 5.43 percent last week. And, rates on one-year adjustable-rate mortgages averaged 4.94 percent this week, down from 5.11 percent last week.

The mortgage rates do not include add-on fees known as points. Each mortgage type carried a nationwide average fee of 0.5 point.