It doesn't matter how many they sold or for how long. What matters is how many sold were dropped in that time frame, and there is no way to know. For all we know, it could be that all P320 pistols that were dropped, discharged, and then again, it could be a very small percentage.
Who keeps these numbers anyway? I would think that Sig would be in the best position to, but then after all this information came out, do you really trust them to tell you? There were reportedly four of these drop-fires, according to reports on the internet, and one police officer who finally sued Sig for getting shot by a holstered pistol. If you were to believe Sig, there were none on the commercial market. They've lost credibility as far as I'm concerned, and I'm sitting here trying to imagine what it would take for them to lose credibility in others minds as well.
I have very little doubt that they knew about the issue, and flat out lied. Then, when it couldn't be hidden anymore, they made a "voluntary upgrade" rather than a full blown recall. They found out there was an issue, and they found the issue, and they found a fix for the issue, and they found out the M17 wasn't effected, all in what seemed like a day.
As it turns out, gun owners will boycott manufacturers that side with politicians who want stricter gun control laws (as they should), but if a manufacturer makes a pistol that is unsafe to the point that dropping it two and a half feet can literally kill you, and then the manufacturer seems very likely to have lied, gun owners will defend them, and call others fickle, and obviously believe that every department that has suspended use of the P320, or every retailer who chose to no longer sell the P320, are overreacting.
Sig stopped production of the P320. Sig offered to fix around half a million pistols, on their dime. If this wasn't a "huge flaw", then my question is, why? If the pistol firing when your finger is not on the trigger is not a "huge flaw", I'm honestly curious what is.