Average fixed mortgage interest rates for long-term contracts rose slightly or held even in the week, the Federal Home Loan Mortgage Corp. said Thursday. Rates for 30-year contracts held steady at 3.87 percent with 0.8 points for the week. A year earlier, 30-year mortgage rates averaged 5.05 percent. The 15-year fixed rate in the week rose from 3.14 percent to 3.16 percent with 0.7 points. In the same week of 2011 the average rate for 15-year loans stood at 4.29 percent. Five-year adjustable rate mortgages averaged 2.83 percent for the week with an average 0.7 points. A week earlier, five-year adjustable rate contracts averaged 2.8 percent. A year earlier, they averaged 3.92 percent. One-year Treasury-indexed adjustable rate mortgages rose in the week from 2.76 percent to 2.78 percent with 0.6 points. \"A strong January employment report added upward pressure to most mortgage rates this week. The economy gained 243,000 jobs last month, the largest monthly gain since April 2011, and the unemployment rate fell to 8.3 percent, which was the lowest since February 2009,\" said Frank Nothaft, Freddie Mac vice president and chief economist.