File photo shows the headquarters of mortgage lender Freddie Mac in McLean
U.S. 30-year fixed-rate mortgages rose slightly to 3.90 percent in the week ending April 19, mortgage financier Freddie Mac said Thursday. REUTERS

U.S. 30-year fixed-rate mortgage rates averaged 3.95 percent in the week ending Dec. 29, according to Freddie Mac.

The rate was up from 3.91 percent, a historic low, in the previous week, but down from 4.86 percent in the previous year.

The average mortgage rate has been at or below 4 percent for nine consecutive weeks.

Mortgage rates ended the year hovering near historic lows in an already affordable housing market, said Frank Nothaft, vice president and chief economist of Freddie Mac, in a statement. It's not surprising then that over 5 percent of households in December plan to purchase a home over the next six months, the highest share since May, according to The Conference Board.

Nothaft predicts that mortage rates will remain very low through at least the middle of 2012. But it remains to be seen if low rates will help a sustained recovery in home sales.

Fifteen-year fixed-rate mortgage rates averaged 3.24 percent in the last week, up from 3.21 percent in the previous week and down from 4.20 percent in the previous year.

Five-year Treasury-indexed adjustable-rate mortages averaged 2.88 percent, up from 2.85 percent in the previous week and down from 3.77 percent in the previous year.

One-year Treasury-indexed ARMs averaged 2.78 percent, up from 2.77 percent in the previous week and down from 3.26 percent in the last year.