U.S. home prices in December fell 2.4% from the year-ago period and 1% from the previous month, according to the latest S&P/Case-Shiller composite 20-city home price index — a barometer for national home prices. Meanwhile, the national index fell 4.1% between the fourth quarter of 2009 and 2010, the lowest annual growth rate since the third quarter of 2009, the report said. Of the 20 cities covered in the S&P/Case-Shiller, 18 reported declines in both the 10-city and 20-city composite indexes in December. This comes on top of nine cities reaching new lows in home prices in November. “Despite improvements in the overall economy, housing continues to drift lower and weaker,” said David Blitzer, Chairman of the Index Committee at Standard & Poor’s. “Unlike the 2006 to 2009 period when all cities saw prices move together, we see some differing stories around the country.” On the positive side of the spectrum, Blitzer said California cities — including Los Angeles, San Diego and San Francisco — saw price gains in the most recent report. Meanwhile, Las Vegas, Phoenix, Miami and Tampa reported new lows in December. Dallas is functioning on its own, staying well below the low price point it hit in February of 2009. Dallas  is one of six cities — including Charlotte, Chicago, Cleveland, Denver and Washington D.C. — that reported gains in their annual growth rates. Write to Kerri Panchuk.