Answer based on context:

There were 167,490 households of which 29.7% had children under the age of 18 living with them, 22.4% were married couples living together, 25.3% had a female householder with no husband present, 6.0% had a male householder with no wife present, and 46.4% were non-families. 39.5% of all households were made up of individuals and 10.7% had someone living alone who was 65 years of age or older. The average household size was 2.29 and the average family size was 3.11.

Which group for households is smaller: married couples living together or non-families?
married couples living together