So much for "stats":
Transport Canada statistics reveal that 60 cyclists were killed in 2001. Of these, 88 per cent were not wearing a helmet, including all of those under age 15.
According to the US Department of Transportation, 90% of cyclists killed in 2000 were not wearing a helmet. In the US, head injuries account for over 60% of cyclist deaths, two-thirds of bicycle-related hospital admissions and one-third of hospital emergency visits for bicycle injuries.
Quoted from the Canadian safety council. You know... people who spend all their time trying to make things safer for us.
I seriously doubt that things have changed much between now and then.
Oh and JWC... I said "head injuries"... not "brain injuries". There's a difference.