Long-term U.S. mortgage rates fell this week for a second straight week amid continued global economic concerns.

Mortgage buyer Freddie Mac says the average 30-year fixed-rate mortgage dipped to 3.54 percent from 3.60 percent last week. That is well below its level a year ago of 4.00 percent.

The average rate on 15-year fixed-rate mortgages declined to 2.81 percent from 2.87 percent.

Deepening doubt about the strength of the U.S. economy and concern that Britons could vote to leave the European Union in a referendum next week are stoking the malaise.