This doesn't actually answer your question Doc, but as a Radiologist, and seeing many people who have crashed, those who ride trikes seem to be older. I believe that would somewhat skew the stats, as people generally slow down some, and are more cautious riders, as they age. Speaking personally, I don't take near the risks now when riding, as I did 20 years ago, and imagine in 20 more years, will ride with more caution than I do now.