context: As of 2010[update], there were 366,273 households out of which 11.8% were vacant. 23.9% of households had children under the age of 18 living with them, 43.8% were married couples, 15.2% had a female householder with no husband present, and 36.4% were non-families. 29.7% of all households were made up of individuals and 7.9% had someone living alone who was 65 years of age or older. The average household size was 2.55 and the average family size was 3.21. In the city, the population was spread out with 23.9% under the age of 18, 10.5% from 18 to 24, 28.5% from 25 to 44, 26.2% from 45 to 64, and 10.9% who were 65 years of age or older. The median age was 35.5 years. For every 100 females there were 94.1 males. For every 100 females age 18 and over, there were 91.3 males.
question: How many of Jacksonville city's residents are older than eighteen?