There were 23,686 households of which 31.8% had children under the age of 18 living with them, 52.3% were Marriage living together, 9.9% had a female householder with no husband present, 3.4% had a male householder with no wife present, and 34.5% were non-families. 27.0% of all households were made up of individuals and 9.5% had someone living alone who was 65 years of age or older. The average household size was 2.54 and the average family size was 3.08.. which household was least common?