Think you would have to get details of all other small choppers first to get a true indication.
In other words ,how many of the opposition are used in training.
A big percentage of R22,s would be used for that in Pomland i reckon.That is when the biggest chance of wrecking them is.
The percentage of mechanical failures causing crashes wouldnt be to high.There has been out of hours parts cause a few but most are pilot error.
That 1 in 6 figure sounds ok.
I usually write off 1 car in every 6 i own