Turns out I was wrong. Youngsters aren't 6% of the vote, but closer to about 9%. Still tiny though. The data indicates people who are registered voters are about twice as likely to become a voter after the age of 25.
You are confused about the difference between percentage of youngsters who vote, which is 40%, and the percentage of the total vote that are youngsters, which is 9%. But 18-24 is probably only 10% of the voting population.
Turns out I was wrong. Youngsters aren't 6% of the vote, but closer to about 9%. Still tiny though. The data indicates people who are registered voters are about twice as likely to become a voter after the age of 25.