Freddie Mac, the mortgage company, reported on Thursday that 30-year, fixed-rate mortgages averaged 5.72% this week, up from 5.67% last week. At the beginning of the year, the 30-year mortgage rate was at 6.07% but then dropped the next week to below 6% and has remained below that threshold for six straight weeks, raising hopes that lower rates will help spur a rebound in the battered housing industry. A year ago, 30-year mortgages stood at 6.30% while rates on 15-year mortgages were at 6.03%. Five-year adjustable-rate mortgages averaged 6.01% and one-year ARMs were at 5.52% this time a year ago.