Population statistics and making inferences

Just playing around with some statistics from the NEA ranking report on school aged population rankings.
It's just interesting to look at the stats.

If we know that:
Alaska (2002) has an estimated 30% of its population aged under 18
and 22.3 percent of the population is aged 5-17, then nearly eight percent of the population is still very young.

Mississippi had the highest population of 5-17 year olds at 35.9 percent. That's huge. That's over a third of the population. Is this normal? This isn't including the percent of the population under 5. Now talk about not having a large voting constituency compared to other states... though you might have a growing population of impressionable voters.