The rate of foreclosures among outstanding mortgages in the Des Moines area dropped to 0.9 percent in May, down from nearly 1.2 percent in May 2014, real estate analytics firm CoreLogic Inc. said. The national foreclosure rate in May was nearly 1.3 percent, while the Iowa rate was 0.87 percent. CoreLogic also said that 3 percent of mortgages were at least 90 days overdue in the metro area, a decline of 0.68 percentage points from the same period last year.