Publication by the Scottish Executive
http://www.scotland.gov.uk/Resource/...71/0015829.pdf

39% of injured cyclists reported they were wearing a helmet at the time
of their accident.

Yet for Scottish cyclists in general 65% never wear a helmet and only
23% wear a helmet on all or most trips. So ~ 23% of the (helmet
wearing) population account for ~40% of injuries.

(Section 6.1, p21)

--
Tony

"The best way I know of to win an argument is to start by being in the
right."
- Lord Hailsham