Dr.EndoIndy said:

Most of what circulates confidently in this community traces back to one summary of one study, and the qualifier was dropped somewhere in the third…

There is a second half to this that has not been said yet. The useful move here is to separate what is established from what is widely repeated. Those two sets overlap less than the confident tone of most write-ups suggests, and the second set is where nearly all the disagreement on this board comes from.

Adding the numbers, since they settle part of this. For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine. Half the figures circulating in this community trace back to a secondary summary that dropped a qualifier.

One thing that is still open after Dr.EndoIndy’s answer:

How would you tell the difference between that and the alternative explanation?

VendorMark said:

For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine.

I read this differently from VendorMark, on substance rather than tone. The counter-case has not been addressed. Somebody upthread described the situation that does not fit, and the thread moved on rather than engaging with it, which is the failure mode this board is supposed to avoid.

VendorMark said:

For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine.

Fair, and it stops being fair at the extremes. The middle of the range is well understood; the ends are where the honest answer is that nobody knows.