Gains in US home prices accelerated in August over July in 14 out of 20 cities monitored in the S&P/Case-Shiller index, the monthly report revealed. Both the 10-city and 20-city composite indexes in the monthly report rose 12.8 percent year-over-year, the report said. On a monthly basis, both indexes rose 1.3 percent, S&P said. Las Vegas set the pace with a 2.9 percent monthly gain, followed by Detroit and Los Angeles with gains of 2 percent. \"Both composites showed their highest annual increase since February 2006,\" said Chairman of the Index Committee David Blitzer. All 20 cities posted gains from August 2012 with 13 of those at double-digit rates. \"Las Vegas and California [San Francisco, Los Angeles and San Diego are all included in the report] continued to impress with year-over-year increases of over 20 percent,\" he said. Denver and Phoenix have posted 20 consecutive annual increases, Blitzer said. Not far behind that, Miami and Minneapolis have each posted annual gains for 19 consecutive months. Holding to an even longer streak, Detroit has posted annual gains for 26 consecutive months. As an anomaly, however, Detroit is the only city among the 20 with a price index that remains below its January 2000 level. The lowest annual gain in August was posted by New York with an increase of 3.6 percent. That is followed by Cleveland with an annual gain of 3.7 percent and Washington with an 12-month increase of 6.3 percent.