There were 13,324 households of which 27.8% had children under the age of 18 living with them, 47.0% were Marriage living together, 10.3% had a female householder with no husband present, 4.3% had a male householder with no wife present, and 38.4% were non-families. 30.2% of all households were made up of individuals and 12.8% had someone living alone who was 65 years of age or older. The average household size was 2.32 and the average family size was 2.87.. Which group was least common?