sentences:  In terms of ancestry, 28.7% were German, 20.7% were Irish, 8.9% were English, and 8.4% were American.Of the 8,486 households, 31.0% had children under the age of 18 living with them, 56.1% were married couples living together, 9.2% had a female householder with no husband present, 29.4% were non-families, and 24.0% of all households were made up of individuals.The average household size was 2.52 and the average family size was 2.96.