The Standard & Poor's/Case-Shiller housing index was released today, and it showed that home prices dropped by the sharpest annual rate on record in January. The index, which monitors housing prices in 20 U.S. cities, revealed that prices have plummeted by 19 percent since January 2008. The statistics for the DC area were in line with the national rate as residential property prices in the city dropped 19.3 percent in the last year.