Now, this is my fourth post on this subject, and I think it is time for a few ground rules. It should be quite clear by now that I am bent on continuing with this system regardless of my critics, so those who wish only to piss and moan at this point are invited to take their comments on the road, to post them on their own blog, where they can speak to their hearts delight about how I am fucking with the laws of nature or whatever.
Comments criticising the methodology will continue to be entertained, but any comment which disparages the overall system on principle will, henceforth from this post on, be deleted. This sort of stick-in-the-mud thinking (however dressed up as intelligensia) is destroying the potential for rational discussion.
The principle flaw in those numbers for classes given on the last post would be that they represent only the minimum age possible with regards to a candidate successfully mastering their class. In the case of mages, where the age range is from 26 to 40, in actual fact only 1 in 64 candidates would succeed at becoming a mage in that time (the DMG gives the age range as 24 +2d8).
So, if you really want to get ambitious, you can work out the number of mages according to their actual successful completion. This isn't as easy as it sounds; I thought I would calculate it out by a) multiplying the total that had reached a certain age by the chance on 2d8 (age 26, 1 in 64: age 27, 3 in 64; age 28, 3 in 64; and so on), while continuing to remove 5% of the candidates for failure ... because they could get to age 36, say, and still fail to become magic users. That's just the way the ball breaks. Some doctors make it through pre-med and med-school, and they fail their internship. Life is a bitch.
But I found out that even without any failure rate, with everyone who reaches age 26 eventually becoming a mage at some point, there are virtually no candidates after age 37. Here's the table I was able to generate (these numbers continue to be per 100,000 population):