sentences:  There were 20,628 households out of which 31.0% had children under the age of 18 living with them.The average household size was 2.90.In the county, the population was spread out with 22.3% under the age of 18, 8.5% from 18 to 24, 12.0% from 25 to 34, 24.1% from 35 to 49, 20.7% from 50 to 64, and 12.40% who were 65 years of age or older.