WASHINGTON (AP) - Average U.S. rates for fixed mortgages edged higher this week for the third straight week but remained low by historical standards. Mortgage buyer Freddie Mac says the average for the 30-year loan rose to 4.53 percent from 4.48 percent last week. The average for the 15-year loan increased to 3.55 percent from 3.52 percent. Mortgage rates peaked in August at 4.6 percent amid expectations the Federal Reserve would reduce its $85 billion a month in bond purchases. The purchases push mortgage and other long-term rates lower. Last month the Fed deemed the economy strong enough for it to reduce the monthly purchases by $10 billion. Mortgage rates are sharply higher than they were a year ago when the 30-year fixed rate was 3.35 percent and the 15-year was 2.65 percent.