18?
If you can't be trusted to buy a pint of Fosters in a pub or a lottery ticket in a corner shop, I'm not sure you can be trusted to decide who runs my kids schools or the hospitals my parents can be treated in.
Voting is a right people have sacrificed everything for, I'm not sure it should be given at 16 as a little more life experience is necessary, IMO. Appreciate everyone does mature at different ages though.