Closing out a year of surprisingly low mortgage interest rates, the average rate for a conventional 30-year home loan was 3.87 percent this week, Freddie Mac said, up slightly from 3.83 percent a week ago.

The home-financing giant reported that the 30-year rate averaged 4.17 percent for all of 2014, following two years of even lower rates. The average for a 15-year fixed-rate mortgage early this week was 3.15 percent, down from 3.55 percent a year ago. The start rates for variable home loans were slightly lower as well, Freddie Mac said.