Could be that the virtual motorcycle is slowly replacing the real one. whens the last time you saw, kids in a tree, kids playing sstreet hocky, kids tramping through the forest on imaaginary african adventures, or building forts.
Not to mention ratio between wage earnings and the cost of a new motorcycle plus, The redicules cost of insurance. Add to this the rising cost of living in general.
Then too comes in the screwball drivers on the road that riders have to watch out for.