WASHINGTON (AP) _ The number of Americans behind on mortgage payments decreased this spring, thanks to plentiful jobs and declining interest rates.

Mortgage delinquencies fell to a seasonally adjusted 4.33 percent in the April-June quarter, down from 4.47 percent during the first three months of the year, the Mortgage Bankers Association of America said Wednesday.

Because unemployment reached a 28-year low of 4.3 percent in the spring, incomes were rising substantially. Also, many borrowers cut their monthly payments because of low interest rates. Adjustable-rate mortgages adjusted downward plus some homeowners with fixed-rate loans were able to refinance.

``The wave of refinancing activity in the first half of the year has helped reduce mortgage debt-service payments as a percentage of disposable (after-tax) personal income to near 15-year lows,'' said Paul Reid, executive vice president of the trade group.

The delinquency rate still was higher than the same quarter a year ago, 4.25 percent. But it should decline further, barring a severe economic downturn, because mortgage rates have declined further.

The average rate on 30-year fixed-rate mortgages hit a five-year low of 6.82 percent last week, according to Freddie Mac, the mortgage company.

Delinquencies declined in three regions and increased in one during the second quarter. They fell from 3.96 percent to 3.62 percent in the West, from 3.93 percent to 3.81 percent in the Midwest and from 4.21 percent to 4.15 percent in the Northeast. However, they rose from 5.21 percent to 5.24 percent in the South.

The delinquency rate is the proportion of mortgages with payments 30 or more days overdue. The association's survey covers 23 million loans, or about half the residential mortgages in the country.

The percentage of loans in foreclosure at the end of the second quarter fell from 1.14 percent to 1.10 percent.