MCLEAN, Va. (AP) — The average rate on a 30-year U.S. mortgage ticked up this week, ending a four-week slide that brought down borrowing costs for homebuyers to the lowest level in nearly a year. The rate rose to 6.3% from 6.26% last week, mortgage buyer Freddie Mac said Thursday. A year ago, the rate averaged 6.08%. Borrowing costs on 15-year fixed-rate mortgages, popular with homeowners refinancing their home loans, also edged higher. The average rate rose to 5.49% from 5.41% last week. A year ago, it ...