In 2000 there were 79,667 households out of which 38.70% had children under the age of 18 living with them, 61.90% were married couples living together, 10.20% had a female householder with no husband present, and 24.20% were non-families. 19.70% of all households were made up of individuals and 6.80% had someone living alone who was 65 years of age or older.  The average household size was 2.72 and the average family size was 3.14.. Approximately how many of the households sampled in 2000 had children under 18 living with them?