Foreclosure rates in Greater Des Moines decreased in December over the same period last year, according to real estate analytics firm CoreLogic Inc. The rate of foreclosures among outstanding mortgage loans was 2.35 percent, compared with 2.48 percent in December 2011. The national rate in December was 2.96 percent. The rate of mortgages that were 90 or more days delinquent dropped to 4.32 percent in December, down from 4.78 percent a year ago, CoreLogic said in a news release.