WASHINGTON (AP) — U.S. long-term mortgage rates shot up this week, yet they stayed close to the historic lows that appear to be helping the real estate market.

Mortgage buyer Freddie Mac says the average rate on the 30-year, fixed-rate mortgage increased to 3.73% from 3.56% last week. The rate averaged 4.65% a year ago, when the higher government debt from President Donald Trump's tax cuts enabled borrowing costs to rise. But as the economic outlook has become less certain, the Federal Reserve has cut interest rates and borrowing costs have tumbled in ways that are generally aiding homebuyers.

The average rate for 15-year, fixed-rate home loans climbed to 3.21% from 3.09% last week.