(Washington, DC)  —  Home prices are showing big gains.  The S&P CoreLogic Case-Shiller National Home Price Index rose more than 18-percent in November from a year ago.  That beat expectations although it’s a slightly slower rate than October’s increase.  Phoenix, Tampa and Miami posted the highest gains on the index’s 20-city composite list with housing prices up more than 25-percent.  Chicago, Minneapolis and Washington, DC showed the smallest annual gains.