According to the latest S&P/Case-Shiller report released today, the U.S. National Home Price Index dropped to 135.8 in the third quarter of this year, down two percent from last quarter.

After rising 4.7 percent in the second quarter of this year, the two percent national decline leaves prices 1.5 percent below their 2009 levels. Of the 20 metro areas analyzed, 18 declined in average prices, with the exception of Las Vegas and Washington D.C. Las Vegas rose 0.1 percent and Washington D.C. rose 0.3 percent.

“While some of the bad numbers may reflect the end of the government’s tax incentive for first time homebuyers, there are other problems weighing on the housing market,” says Standard & Poor’s Chairman of the Index Committee, David M. Blitzer. “The national economy is certainly the number one issue for housing. Additionally, there is a large supply of houses on the market and further, hidden, supply due to delinquent mortgages, pending foreclosures or vacant homes.”

For more information, download the entire S&P/Case-Shiller report.