WASHINGTON (MarketWatch) -- U.S. home prices advanced by 0.7% in January to stretch the year-on-year advance to 9.7% -- the largest year-on-year gain since April 2006, according to CoreLogic. "With these gains, the housing market is poised to enter the spring selling season on sound footing," said Mark Fleming, CoreLogic chief economist, in a statement. From the peak, prices nationally have shrunk by 26.4%, or a 19.9% when distressed transactions are excluded. All but two states, Delaware and Illinois, are experiencing year-over-year price gains. Arizona led the way with a 20.1% surge. CoreLogic's pending home sales rise forecasts a 0.3% decline in February but a 9.7% year-on-year gain.