Mortgage rates dipped slightly this week to an average 6.69 percent for a 30-year fixed term, according to a data from Freddie Mac. The rate was down from 6.74 percent last week, an 11-month high level. The decline was attributed to housing reports suggesting a longer-than-expected housing slump. Rates on 15-year fixed mortgages fell to 6.31 percent from 6.37 percent. On a year-over-year basis, mortgage rates for 30-year fixed mortgages were down from 6.71 percent and 15-year mortgage rates were down from 6.36 percent.