Pittsburgh's residential real estate market continued to sputter in February, with Allegheny County posting a 16.4 percent drop in sales from the same month last year. Just 896 residential properties -- including houses and condos -- sold in Allegheny County in February 2008, down from 896 in February 2007, according to the report issued Thursday by RealSTATs, a real estate information company based on Pittsburgh's South Side. Residential sales dollar volume dropped 7.5 percent year over year for the five-county region, led by Allegheny County with a decline of $12.3 million.