Mortgage rates took a turn upward in the week ending April 9, according to Freddie Mac's (FRE) Primary Mortgage Market Survey released Thursday. 30-year fixed-rate mortgages averaged 4.87 percent with an average 0.7 point, up from last week's 4.78 average, but well below the average last year at this time -- 5.88 percent. “Mortgage rates rose slightly this week but still remained historically low,” said Frank Nothaft, Freddie Mac vice president and chief economist.  “Interest rates for 30-year fixed-rate mortgages have averaged below 5.0 percent for the last four weeks, which should keep homeowner affordability at record levels." This week's 15-year fixed-rate mortgage averaged 4.54 percent, up slightly from last week's 4.52 percent average, which marked the lowest 15-year FRM in the life of Freddie Mac's weekly survey. At this time last year, the 15-year FRM averaged 5.42 percent. The survey found Five-year Treasury-indexed ARMs averaged 4.93 percent this week, up from last week's average of 4.92 percent, and One-year Treasury-indexed ARMs averaged 4.83 percent, compared to 4.75 percent last week. “Given these low rates, housing demand has strengthened," Nothaft said. "Conventional mortgage applications both for refinancing and for home purchases have increased over the past five consecutive weeks ending April 3."  Since the end of February, applications for home purchases were up about 22 percent and nearly 129 percent for refinancing, according to the Mortgage Bankers Association. A separate rates survey conducted by Bankrate.com also found that mortgage rates climbed this week. According to  Bankrate, the benchmark 30-year fixed-rate rose 7 basis points to 5.2 percent, while the benchmark 15-year fixed-rate increased 2 basis points to 5.27 percent. Write to Kelly Curran at kelly.curran@housingwire.com. Disclosure: The author held no relevant investment positions when this story was published. Indirect holdings may exist via mutual fund investments. HW reporters and writers follow a strict disclosure policy, the first in the mortgage trade.