In the county, the population was distributed as 25.80% under the age of 18, 9.50% from 18 to 24, 28.80% from 25 to 44, 22.10% from 45 to 64, and 13.80% who were 65 years of age or older.  The median age was 36 years. For every 100 females, there were 91.70 males.  For every 100 females age 18 and over, there were 87.70 males.. Which age group had the smallest percentage of people?