An index by the National Association of Home Builders (NAHB) designed to track improving housing markets across the country has added nine more metro regions while dropping two cities. The November additions -- Cheyenne, Wyo.; Corpus Christi, Texas; Davenport, Iowa; Fort Collins, Colo.; Hinesville, Ga.; Lima, Ohio; Monroe, La.; Tyler, Texas; and Williamsport, Pa. -- raise the number from 23 to 30 metro areas.