It wasn't so long ago I asked you for this figure, and your response was to accuse me of being prejudiced against bikers.
I take it that you understand now that it's a significant enough amount to have to take it into account when considering road safety for bikers?
I'd say that in sole vehicle accidents, road contamination is a major factor in regard to motorcycles.
I've come off on black ice, gravel, and diesel in the time I've ridden on the road, and 'the marbles' (shreds of rubber of tyres) on the track.
Come to think of it, of the 'offs' I've had over the years when I've been riding the bike, they have all been due to road contamination or black ice (the black ice was in a straight line at about 25mph when I hit a pothole when I was 17).