WASHINGTON — The average rate on the 30-year fixed mortgage fell again this week to a record low. The eighth record low in a year is attracting few takers because most who can afford to buy or refinance have already done so.

Mortgage buyer Freddie Mac said Thursday that the average rate on the 30-year fixed mortgage dipped to 3.88 percent this week, down from the old record of 3.89 percent one week ago.

The average on the 15-year fixed mortgage ticked up to 3.17 percent from 3.16 percent, which was also a record low. Records for mortgage rates date back to the 1950s.

Mortgage rates tend to track the yield on the 10-year Treasury note, which fell below 1.9 percent this week.

For the past three months, the 30-year fixed mortgage rate has hovered near 4 percent. Yet cheap rates on the most popular mortgage option have done little to boost home sales.

Mortgage applications have risen about 6 percent on a seasonally adjusted basis over the past four weeks, according to the Mortgage Bankers Association. But they are coming off extremely low levels.

The average rates don’t include extra fees, known as points, which most borrowers must pay to get the lowest rates. One point equals 1 percent of the loan amount.