I did a survey on the road forum a few years ago wherein I asked how many folks had had their lives saved by their helmets. It was running about 50% "yes" until, for some odd reason, the thread was dumped into A&S. (So far as I know, there was not a single mention of guns, so the move remains completely inexplicable to me.)

At any rate, it should be obvious that cycling in the pre-helmet days had nothing close to a 50% fatality rate. So I'm not completely convinced of the usefulness of surveys on the subject, except perhaps to illustrate the point that today's cyclist appears to grossly overestimate the risks of bicycling and the effectiveness of bicycle helmets.