mortgage rates finally ended their sixweek ascent but remain at levels not seen since 2008 housingfinance agency freddie mac said in the week ending thursday the average rate on a 30year fixedrate mortgage rose to 666 from 670 last week a year ago the average rate was 299 average 15year rates were 590 down from 596 last week freddie mac said a year ago the 15year fixedrate mortgage rate averaged 223 the average rate on a fiveyear treasuryindexed hybrid adjustablerate mortgage or arm was 536 up from 530 last week a year ago the fiveyear arm averaged 252 mortgage rates decreased slightly this week due to ongoing economic uncertainty said sam khater freddie macs chief economist however rates remain quite high compared to just one year ago meaning housing continues to be more expensive for potential homebuyers