Average mortgage rates for long-term, fixed-rate loans keep falling to record lows, the Federal Home Loan Mortgage Corp. said Thursday. Average rates for 30-year contracts dropped from 3.79 percent to 3.78 percent with 0.8 points, a record low. Thirty-year mortgage rates averaged 4.6 percent the same week of 2011. Average rates on 15-year contracts held at a record low of 3.04 percent with 0.7 points, Freddie Mac said. A year earlier, rates on 15-year contracts stood at 3.78 percent. Five-year adjustable rate mortgages averaged 2.83 percent in the week with an average 0.6 points, unchanged in the week and down from an average of 3.41 percent a year earlier. Average rates on one-year treasury-indexed adjustable mortgages fell from 2.78 percent to 2.75 percent with 0.4 points. A year ago, rates for these loans averaged 3.11 percent. \"Mortgage rates were virtually unchanged this week with fixed-rate loans remaining at record lows and helping to drive homebuyer affordability,\" commented Freddie Mac Vice President and Chief Economist Frank Nothaft.