WASHINGTON (AP) — Average rates on U.S. long-term fixed mortgages remained steady for a second straight week, giving prospective home buyers more time to lock in historically low levels.Mortgage buyer Freddie Mac said Thursday that the average rate on the 30-year loan remained unchanged at 4.4 percent this week. That is a full percentage point higher than in early May, when rates neared record lows. Still, rates remain low by historical standards.The average on the 15-year fixed loan edged up to 3.44 percent from 3.43 percent.Mortgage rates spiked in June after Chairman Ben Bernanke indicated that the Federal Reserve could slow its bond purchases this year.