The average long-term U.S. mortgage rate rose again this week, reaching its highest level in nine months, another setback for prospective homebuyers. The benchmark 30-year fixed rate mortgage rate rose to 6.53% from 6.51% last week, mortgage buyer Freddie Mac said Thursday. Despite the latest increase, the average rate remains below 6.89%, where it was a year ago. When mortgage rates rise they can add hundreds of dollars a month in costs for borrowers, reducing their purchasing power. Rates