WASHINGTON (AP) -- Average U.S. rates for 30-year and 15-year fixed mortgages fell to fresh record lows this week, offering more incentive for Americans to buy or refinance homes.

Mortgage buyer Freddie Mac says the rate on the 30-year loan fell to 3.84 percent, the lowest since long-term mortgages began in the 1950s. That's below the previous record rate of 3.87 percent reached in February.

The 15-year mortgage, a popular option for refinancing, dropped to 3.07 percent, also a record. The previous record of 3.12 percent hit last week.

Mortgage rates have been below 5 percent for the past year. Yet homes sales have slumped and remain well below healthy levels.