Not quite. The 1e and 2e gazetteers made it clear that non humans were rare in human settlements until 3e re-jigged the numbers for LG play.But, that's the thing. You don't get to pick and choose. It's not like it was rare for classed casters to be present in virtually every listed settlement. Did you have magic shops? Well, no. Of course not. That wasn't a thing in AD&D. But, this idea that it would be weird to see a non-human in Greyhawk just ignores far too much of what was presented. Greyhawk might not be as high magic as, say, Faerun, fair enough. But that hardly makes it low magic.
I just don't know where this idea comes from. And why it persists. It's such a bizarre read on the material.
There was then an outline of the high-level NPC class distribution (high being level 10+) in the 1983 boxed set:
cleric types: 15%
fighter types: 50%
magic-user types: 10%
thief types: 24%
others: 1%
So a whopping 74%+ of npcs were purely martial. Obviously, there would need to be a slight adjustment for new classes and this would vary by location. Rel Deven with its wizard and artificer school is going to have more of them than average.
In the 2E High Level Campaigns supplement: for every NPC of level x, there are half as many of level x+1. Thus, in a small city of 10,000, there will be 100 classed NPCs, roughly as follows:
- 50 1st-level
25 2nd-level
13 3rd-level
6 4th-level
3 5th-level
2 6th-level
1 7th-level