In the county, the population was spread out, with 17.40% under the age of 18, 15.70% from 18 to 24, 44.30% from 25 to 44, 19.40% from 45 to 64, and 3.30% who were 65 years of age or older. The median age was 31 years. As of 2014, the life expectancy in Summit County was 86.83 years, the longest average life expectancy of any county in the United States. For every 100 females there were 139.00 males. For every 100 females age 18 and over, there were 144.90 males.