I know that I have seen/had more broken ones than good ones.
With HK/T/G style wheels it is the opposite. I have seen more with the outer rim material cracked or shrunken
than with the outer rim metal broken like HQ/Z type ones.
But this I have always put down to the fact that the outer loop on the HK/G ones is a solid steel band as opposed
to the HQ/Z ones being for lack of a better word a perforated steel ring.
As to why they broke other than from accidents, my main thought was overloading or simple fatigue.
I would also think that what they were from would make a difference as in a power steered car would put less load on the wheel than
a non steered car.
Add wide wheels to a non power steered car and I can see that the load on them will be much higher as well.

So has anyone else come across more good original ones than bad ones.
Cheers Paul.