Greater Baltimore’s foreclosure rate remained below the national average in the first quarter, but the number of filings increased 141%, according to data released Thursday. The Baltimore-area registered 6,515 foreclosure properties during the quarter — up 141% from the period a year earlier — with 0.59 of its housing units receiving a foreclosure filing during the quarter. That’s according to Irvine, Calif.-based RealtyTrac’s Q1 2010 Metropolitan Foreclosure Report. The Baltimore-area numbers, however, declined 1.32% from the fourth quarter of 2009.