The weekly mortgage rate reports released Thursday by Freddie Mac and Bankrate were mixed. But one thing was certain: the average rate for 30-year fixed-rate mortgages hit a new record low.

According to Freddie Mac’s Primary Mortgage Market Survey, 30-year fixed-rate mortgages averaged 4.57 percent with an average 0.7 point for the week ending July 8, 2010, inching down from last week’s average of 4.58 percent. Freddie Mac said this rate marked yet another all-time low in its 39-year survey.

Bankrate also reported a decline in 30-year fixed-rate mortgages. According to its weekly mortgage survey, rates averaged 4.74 percent with an average 0.39 point

this week, falling from last week when 30-year fixed-rate mortgages averaged 4.75 percent.

The story was different for 15-year fixed-rate mortgages, though.

Freddie Mac said 15-year fixed-rate mortgages averaged 4.07 percent with an average 0.7 point this week, edging up from 4.04 percent one week earlier. And Bankrate said 15-year fixed-rate mortgages came in at 4.22 percent with an average 0.36 point, a minor uptick from last week’s average of 4.2 percent.

Despite the slight increase in 15-year fixed-rate mortgages, both Fannie Mae and Bankrate noted that on an overall basis, mortgage rates continued to linger near ultra-low levels, a benefit to homebuyers and refinancers alike.

“With mortgage rates falling to historic lows, refinance activity has been strong over the past three months,” said Frank Nothaft, Freddie Mac VP and chief economist.

“The Bureau of Economic Analysis reported that the effective mortgage rate of all loans outstanding was just below 6 percent in the first quarter of 2010, the lowest since the series began in 1977,” Nothaft said. “Since the start of the second quarter, two out of three mortgage applications on average were for refinancing, according the Mortgage Bankers Association.”