I don't believe G Louis. He came into our room at CES once, insisting that the polarity was off in our system without even sitting down to make his revelation. I flipped the switch (which has been a part of the MP-1 preamp circuit since its inception). At that point he said it was only audible on CD- not LP (which was the second sign of baloney).
I had the same cut on CD and played it- he didn't see that one coming... At that point he insisted that if it was recorded analog, but encoded to CD, you couldn't hear it. What nonsense.
The thing was, it sounded better the way we had it. The recording in question was done with two mics (Canto General). He made a hurried exit, apparently aware he had embarrassed himself.
50% is about right. Mastering engineers are not worried about whether their equipment inverts polarity or not. So its just statistics.