By Greg Robb
WASHINGTON (MarketWatch) -- The prices of single-family homes in 20 major cities rose a non-seasonally unadjusted 0.6% in July, according to the Case-Shiller home price index released Tuesday by Standard & Poor's. Prices have moved up 3.2% in the past year, down from 4.2% in June. Prices rose in 12 of the 20 metropolitan areas tracked by Case-Shiller in July compared with June. Economists expect home prices to moderate in coming months as demand as slowed.