Well, I see we are still swagging away.

But helmeted riders have a serious trauma rate (medical attention sought for an injury) on the order of once every 20 years.
Unhelmeted riders have a serious trauma rate (medical attention sought for an injury) on the order of once every 8 years.

(Trauma, that is injury with self care, about once every 5 years.)

Your choice.

-mr. bill