Mortgage interest rates rose again this week but remain lower than a year ago, and the average rate for a traditional 30-year, fixed loan for 2010 was the lowest in 55 years, according to Freddie Mac. The government-sponsored enterprise said its primary mortgage market survey showed the average rate for a 30-year, fixed mortgage rose to 4.86% for the week ending Thursday, up from 4.81% a week earlier. A year ago, the average rate was 5.14%. “For the year as a whole, 30-year fixed mortgage rates averaged just below 4.7%, which represented the lowest annual average since 1955 when the average price of a home was $22,000,” according to Freddie Mac chief economist Frank Nothaft. Earlier in December, Nothaft said he expects rates on a 30-year, fixed mortgage to remain below 5% throughout 2011, as the economic recovery accelerates. The average rate for a 15-year, fixed mortgage increased to 4.2% from 4.15% the prior week, according to the Freddie Mac survey. Interest rates for the traditional 30-year mortgage dipped to as low as 4.07% in early November, according to real estate research firm Zillow. Freddie Mac reported 30-year, fixed rates hit 4.17% in early November. Freddie Mac said the average five-year, adjustable-rate mortgage increased to 3.77% this week from 3.75% a week earlier but is down from 4.44% a year ago. The average rate for a one-year, ARM fell to 3.26% from 3.40% a week ago. The rate is down from 4.33% at this time last year. Write to Jason Philyaw.