In the city, the population was spread out with 28.1% under the age of 18, 9.2% from 18 to 24, 26.2% from 25 to 44, 21.4% from 45 to 64, and 15.1% who were 65 years of age or older.  The median age was 36 years. For every 100 females, there were 83.5 males.  For every 100 females age 18 and over, there were 77.7 males.. What age group made up the largest percentage of the population?