Mortgage rates rose this week to the highest level in a year, mortgage buyer Freddie Mac said Thursday. Freddie Mac's latest Primary Mortgage Market Survey, released Thursday, showed the average rate on the benchmark 30-year fixed mortgage climbed to 6.66% from last week's reading of 6.58%. The average rate on a 15-year fixed mortgage rose to 6.04% from last week's reading of 5.96%. Mortgage rates are affected by several factors, including the Federal Reserve and geopolitics. FED POLICYMAKERS LEAVE RATES UNCHANGED AMID ELEVATED UNCERTAINTYThough mortgage rates are not directly affected by the Fed's interest rate decisions, they closely track the 10-year Treasury yield.