There are 27,908 households, of which 31.5% have children under the age of 18 living with them, 48.9% were married couples living together, 15.4% had a female householder with no husband present, and 32.3% were non-families. 28.4% of all households are made up of individuals, and 10.6% had someone living alone who was 65 years of age or older. The average household size was 2.39, and the average family size was 2.94. 70% of women with school-age children work.. which household was least common?