Okay! As promised, this is the math.
So this is from the 2e (well, 2.5...) book Dungeon Master's Options: High Level Campaign. Specifically from chapter 1, a 23 page affair that has great guidance for anyone running a campaign ... at almost any levels really. Page 21-22 has a very relevant section on demographic.
So on a "roll 3d6 in order" stat set for generic humans, they figured out the portion that would meet the "requirement" to be a hero: a stat of 15 in a prime requisite, a con no lower than 9, and no other score lower than 8. About 1/10 people meet these requirement. That's interesting.
Now, then then figured that half of those would be level 2. Why half? Well a lot of them die, or have retired, haven't leveled up yet, or don't have the ambition. So 1/20 is level 2. And half of that is level 3, so one in 40.... and so on and so forth.
If you keep this up, you end with about 16 out of 1 million people are at level 14. and 1 out of 1 million are at level 18!
And of those 16 level 14
PCs, you will be lucky if *one* of them is a transmuter...
For the retired transmuter though, this power is a *great* deal! It's almost free money.