http://www.ots.ca.gov/Media_and_Rese...ing_Survey.pdf
http://www.nbclosangeles.com/news/po...150197075.html
Why research was done in California....... Drum roll..... Because it's legal aka controlled environment.
Reason 2: more riders do it there because of reason number one and thus you have a big pool of diverse riders to give you a big picture all all types of scenarios which in hand give you very reliable research statistics.
If you do not understand statistics or the concept of research, please read up and come back with questions regarding it so you can better understand.
And if you have read any of the links I posted, you will notice a decrease in moto accidents due to awareness because of education. Motorcycle awareness month ring a bell?
http://www.trafficsafetymarketing.gov/ShareTheRoad
http://www.nhtsa.gov/Safety/Motorcycles