The average long-term U.S. mortgage rate dropped for the third week in a row, easing borrowing costs for prospective homebuyers as the spring homebuying season rolls on.

The benchmark 30-year fixed rate mortgage rate fell to 6.23% from 6.3% last week, mortgage buyer Freddie Mac said Thursday. One year ago, the rate averaged 6.81%.

The average rate is now at its lowest level since March 19, when it was 6.22%.

Meanwhile, borrowing costs on 15-year fixed-rate mortgages, popular with homeowners refinancing their home loans, also eased this week. That average rate dropped to 5.58% from 5.65% last week. A year ago, it was at 5.94%, Freddie Mac said.

Mortgage rates are influenced by several factors, from the Federal Reserve’s interest rate policy decisions to bond market investors’ expectations for the economy and inflation.