Tampa Bay home prices slid 21.3 percent from April 2008 to April 2009, but the one-month price change suggests housing values could be stabilizing, according to the S&P Case-Shiller home price index released Tuesday. Local home prices fell 0.7 percent from March to April. That compares with a 2.7 percent plunge from February to March. The Tampa Bay price decline was the seventh-steepest on the 20-city housing index. Prices in Phoenix fell annually by 35.3 percent. Las Vegas wasn't far behind with a drop of 32.2 percent. Miami home prices fell 27.3 percent. Two Midwest trouble spots were Detroit and Minneapolis, where prices fell 25.4 percent and 22.1 percent respectively.