WASHINGTON (AP) - Average U.S. rates for fixed mortgages barely changed this week, hovering near historically low levels.Mortgage buyer Freddie Mac said Thursday that the average for the 30-year loan slipped to 4.51 percent from 4.53 percent last week. The average for the 15-year loan edged up to 3.56 percent from 3.55 percent.Mortgage rates have risen more than a full percentage point since hitting record lows a year ago. The increase was driven by speculation that the Federal Reserve would reduce its $85 billion a month in bond purchases.Last month, the Fed determined the economy was strong enough to start cutting those monthly purchases by $10 billion. The bond purchases have kept long-term interest rates low.The rise in mortgage rates has slowed home sales, which have fallen for three straight months.But overall, 2013 represented the best year for the housing market since the financial crisis. Sales of existing homes should reach 5.1 million for last year, the National Association of Realtors forecasts. That would be up 10 percent from the previous year and the most since 2006. It's still below the 5.5 million generally associated with healthy housing markets.Most economists expect sales and prices to keep rising this year, but at a slower pace. They forecast sales and prices will likely rise around 5 percent, down from double-digit gains in 2013.To calculate average mortgage rates, Freddie Mac surveys lenders across the country between Monday and Wednesday each week. The average doesn'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.The average fee for a 30-year mortgage declined to 0.7 point from 0.8 point. The fee for a 15-year loan slipped to 0.6 point from 0.7 point.The average rate on a one-year adjustable-rate mortgage was unchanged at 2.56 percent. The fee stayed at 0.5 point.The average rate on a five-year adjustable mortgage increased to 3.15 percent from 3.05 percent. The fee was unchanged at 0.4 point.