Mortgage applications in America fell for a third straight week as home purchases declined to the lowest level since November 2003, adding to evidence housing will keep slowing.

The Mortgage Bankers Association’s index of applications to buy a home or refinance an existing loan decreased 3.7% to 548.6, the lowest level this year, from 569.6. The gauge of purchase applications dropped 4.4% to 389.4.

The rise in borrowing costs this year is chipping away at home sales and reducing refinancing, which has been a source of cash for Americans through the current expansion. As the housing market limps along, economic growth will depend more on job growth and business spending in coming months, economists said.

“Recent increases in mortgage rates can be expected to depress home sales further over the next few months,” an economist at JPMorgan Chase & Company, Robert Mellman, said.

The mortgage banker’s refinancing index fell 2.4% last week to 1489.4, the lowest since the last week of December.

The average rate on a 30-year fixed mortgage has risen almost half a percentage point this year. Last week, the rate fell to 6.53% from 6.56%.

At last week’s average rate, monthly principal and interest costs for each $100,000 of a loan would be $634. A year ago, when the average was 5.75%, the payment was $584.

The one-year adjustable mortgage fell to 5.96% from 6% a week earlier.

The Mortgage Bankers Association’s survey covers about half of all American retail residential mortgage originations and has been compiled every week since 1990.