Home prices fell in December for a fourth consecutive month in most big U.S. cities, as modest sales gains in the depressed housing market have failed to lift prices, according to a report released Tuesday. The Standard & Poor\'s/Case-Shiller home-price index showed prices fell in December in 18 of 20 cities tracked, but the declines partly reflect the typical slowdown seen in autumn and winter. Still, prices fell in 19 of the 20 cities in December compared to the same month in 2010. Nationally, prices have fallen 34 percent since the housing bust, or back to levels last seen in 2002. A gauge of quarterly national prices, which covers 70 percent of U.S. homes, fell to its lowest point on records dating back to 1987 after being adjusted for inflation. \'The pick-up in the economy has simply not been strong enough to keep home prices stabilized,\' said S&P index committee chairman David Blitzer. \'If anything, it looks like we might have re-entered a period of decline as we begin 2012.\'