WASHINGTON (AP) – Long-term U.S. mortgage rates rose this week, lifting from their 2016 lows but remaining historically low during the spring home-buying season. Mortgage buyer Freddie Mac says the average 30-year fixed-rate mortgage increased to 3.66 percent from 3.59 percent last week. That brought it close to its level a year ago of 3.68 percent. The average rate on 15-year fixed-rate mortgages advanced to 2.89 percent from 2.85 percent last week.