Probability of Opportunity Fire - was it ever tested?

[BigDuke66]

Gentlemen,
Just wonder if anyone ever made the attempt to find out the probability of triggering OF.
With the latest patch series I have the feeling that OF triggers now more often, and somewhere in an older thread there had been talk about changing the probability of OF, changelog doesn't mention such a change for any of the Napy games but I wouldn't wonder if such a change would have been kept out of it. There never seems to have been any solid info of OF and it's probability.