Helmet week - Should helmets be mandatory for all ages?.

I have done some little research on the Helmet laws. Apparently in New Zealand is the only country where it is mandatory for all ages. In the US there are certain states that also have this regulation.

Other countries such as Canada require it only for children until they are 18. I know in the Netherlands and the UK it is not mandatory, it's the responsibility of the parent or the rider.

What do you think? Safety first? By law or is it one's own responsibility?

http://www.cyclehelmets.org/mf.html?1019

http://www.cycle-helmets.com/zealand_helmets.html

http://www.cycle-helmets.com/england_helmets.html 

http://staff.washington.edu/chudler/bikelaw.html