Long-term mortgage interest rates fell to 31-month lows this week, according to data from Freddie Mac, as investors continue to worry about international trade disputes. The average rate on a 30-year fixed-rate mortgage dropped to 3.73% with an average 0.5 point during the week ended June 27, down from 3.84% last week and down from 4.55% a year ago. Freddie Mac says that falling rates have pushed mortgage applications up five percentage points over the past month.