The average long-term U.S. mortgage rate eased for the second week in a row, but remains elevated compared with this time last year. The benchmark 30-year fixed rate mortgage rate fell to 6.65% from 6.67% last week, mortgage buyer Freddie Mac said Thursday. One year ago, the average rate was 6.58%. Borrowing costs on 15-year fixed-rate mortgages, often sought by borrowers refinancing a home loan, also eased this week. That average rate dropped t…