SILVER SPRING, Md.—Average long-term U.S. mortgage rates moved slightly higher in the final week of 2021. Mortgage buyer Freddie Mac reported Thursday that the average rate on the benchmark, 30-year home loan ticked up to 3.11 percent this week from 3.05 percent last week. A year ago, the 30-year rate stood at 2.67 percent. The average rate on 15-year, fixed-rate mortgages, popular among those refinancing their homes, rose to 2.33 percent from 2.3 percent last week. It was 2.17 percent a year ago. Many economists expect rates to rise next year after the Federal Reserve announced earlier this month that it would begin dialing back its monthly bond purchases—which are intended to lower long-term rates—to combat accelerating inflation. But even with the expected three rate increases next year, the Fed’s benchmark rate would still be below 1 percent. Despite historically low interest rates, many would-be home buyers have missed out …