In 2000, there were 149,957 households out of which 18.30% had children under the age of 18 living with them, 52.70% were Marriage living together, 7.70% had a female householder with no husband present, and 37.00% were non-families. 30.40% of all households were made up of individuals and 16.90% had someone living alone who was 65 years of age or older.  The average household size was 2.13 and the average family size was 2.61.. which household was least common?