U.S. home prices headed higher in June in all 20 monitored markets in a closely watched monthly report, but some gains slowed, Standard & Poor\'s said Tuesday. The S&P/Case-Shiller Home Price Indices showed gains from May to June and on an annual basis in all 20 cities, the report said. The gains were not entirely consistent, however. In only six cities were prices rising faster than in the previous report, compared to 10 in May, the report said. For the second consecutive month, however, the home price indexes for Dallas and Denver hit all-time highs with prices up 1.7 percent in June in both markets. From March 2009 lows, San Francisco has made the largest gains with prices up 47 percent since then. In Phoenix, with the second largest gain, prices are up 37.1 percent from the recessionary low, which occurred in September 2011. In June, the 10-city and 20-city composites posted gains of 2.2 percent month to month. Over 12 months, the 10-city index is up 11.9 percent, while the 20-city index is up 12.1 percent. \"National home prices rose more than 10 percent annually in each of the last two quarters,\" said Chairman of the Index Committee David Blitzer in a statement. \"However, the monthly city by city data show the pace of price increases is moderating,\" he said. \"Other housing news is positive, but not as robust as last spring,\" Blitzer said, pointing to construction starts and sales of new homes that lag behind the pace set by sales of existing homes. \"Despite recent increases in mortgage interest rates, affordability is still good as credit qualifications have eased somewhat,\" he said. The report shows annual gains up 24.9 percent in Las Vegas, the largest increase among the 20 markets included in the report, followed by 24.5 percent in San Francisco and 19.9 percent in Los Angeles. From May to June, the highest gain was a 3.4 percent increase in Atlanta, followed by 3.3 percent in Chicago and 2.8 percent in Las Vegas and in San Diego, Calif.