the life span of deer recovery machines may have been 33%, however not all machines were deer recovery, so loss rate would have been lower.
The 10% was talked about in the mid 90's. serious deer recovery was a distant memory by then, with most full time deer operators moving up from D's and E's all the way to 300's and 22's, such was the economics of it by then.
Also in the 90's we had between 3-500 helicopters, not the 850 odd that we now have, so 10% would have been 30-50, i guess that is possible.