Long-term U.S. mortgage rates ticked up this week for the second straight week, remaining substantially higher than a year ago amid strength in the economy.

Mortgage buyer Freddie Mac says the average rate on 30-year, fixed-rate mortgages rose to 4.54 percent from 4.52 percent last week. Long-term loan rates have been running at their highest levels in seven years. The average benchmark 30-year rate reached a high this year of 4.66 percent on May 24. By contrast, the rate stood at 3.78 percent a year ago.

The average rate on 15-year, fixed-rate loans edged up to 3.99 percent this week from 3.97 percent last week.