There were 22,000 households of which 37.1% had children under the age of 18 living with them, 48.3% were Marriage living together, 12.7% had a female householder with no husband present, 5.1% had a male householder with no wife present, and 33.9% were non-families. 26.7% of all households were made up of individuals and 7.5% had someone living alone who was 65 years of age or older. The average household size was 2.70 and the average family size was 3.24.. Which groups in average are under 4 in size?