Peasants, Nobles, Mages, Normals, and Heroes - How Many NPCs have Levels?

  A discussion my sons and I were having recently was - in 1e how many NPCs have levels and what are they? We have always assumed that player characters are 'over and above' NPC numbers, but we were curious as to what those numbers are. I'll walk you through what we did to see if you agree.
  Please remember that my 1e campaign is a relatively low-level, low-magic world.
  Let's see if we can figure out the assumptions made by EGG.
  When you look at the DMG you see that the rules for henchmen talk about the numbers for leveled characters in "an active adventuring area" could be as high as 1 in 50 while is settled areas as low as 1 in 5,000! If we assume that those are the extremes we can guess that the total number is, oh, 1 in 1,000. This means that in a nation the size of the Kingdom of Seaward (my 1e campaign setting) my which has a population of about 780,000 there would be about 780 NPCs with levels.
  It also looks like there are twice as many 1st level characters as 2nd level and twice as many 2nd level as 3rd level, etc. Yes, thuis is just an impression. It also looks like (based on notes in the Hirelings section) that most NPCs are 3rd level or below (up to third level = enlisted or NCO, 4th level+ = officer).
  Since I am already waving my hands hard enough to flutter papers, let's assume 50% of all NPCs with levels are 1st level and each higher level is half as common.
  So, this means that my breakdown of those NPCs in Seaward would look roughly like this
1st level - 390 NPCS
2nd - 195
3rd - 92
4th - 46
5th - 23
6th - 12
7th - 6
8th - 3
9th - 2
10th - 1

  OK, while there are about 2,000 assumptions going on there, I can live with this. But what classes are they?
  Once again, the henchmen section gives us a hint. According to it we should expect the NPC population to be:
35.2% Fighters
17% Clerics
17% Magic-users
12.5% Thieves
4.4% Paladins
4.4% Rangers
3% Druids
3% Illusionists
2.5% Assassins
1% Monks

  Or to break down this list even further, the 1st level NPCs should look like this;
138 1st level Fighters
67 1st level Clerics
66 1st level Magic-users
50 1st level Thieves
17 1st level Paladins
17 1st level Rangers
12 1st level Druids
11 1st level Illusionists
10 1st level Assassins
3 1st level Monks
  [note: I rounded up a few]
 
  While this may look like a lot, this means that 1 in every 5,620 Seawardians is a 1st level fighter - that isn't shocking.

  Let's look at 5th level and look just at the 'big four' (fighter, cleric, magic-user. thief) at first to get a rough idea. The rough numbers are;
10 5th level Fighters
5 5th level Clerics
4 5th level Magic-users
3 5th level Thieves
1 'left over' by rounding [note that I rounded Clerics up and Magic-users down].

If we use the 'expanded' percentages, it looks like this;
8 5th level Fighters
3 5th level Clerics
3 5th level Magic-users
3 5th level Thieves
1 5th level Paladin
1 5th level Ranger
1 5th level Druid
1 5th level Illusionist
1 5th level Assassin
1 5th level Monk
  [by rounding up the 'marginal' classes we account for all 23 NPCs]

Well, that is interesting! Only 3 5th level magic-users in the Kingdom? Mentors might be hard to come by!

  For the rarefied heights of upper levels we concluded we'd just use the table for henchmen in the DMG and let the dice roll as they may.

  I really look forward to your comments about my 2,000 assumptions

  Now, when we were discussing this we came to 2 main points;
  1) this OBVIOUSLY can't include PCs!
  2) NPCs placed by the DM probably shouldn't count, either.

  Let's get back to assuming things from the DMG.
  The section on henchmen says that a fair number of even 1st level guys are either  not interested in the high risk life of adventuring or 'already in a situation they are satisfied with', i.e., a job that doesn't suck too hard. The percentage of those timid + happy leveled types out of the total appears to be as low as 50% in the oft-mentioned 'active adventuring area', as high as 98% in settled areas with it being about, oh, 90% as an average. So it looks like at any given time there are 13-14 1st level fighters that would be willing to become henchmen, if you can find them!
  Conversely, this also points to 125 1st level fighters having employment in the kingdom.

  Once long ago I was playing a 7th/7th Cleric/magic-user in Lew Pulsipher's campaign on an adventure and we rode into a town to ask questions. When my character introduced himself the headman swept off his hat, tugged his forelock, and treated my character with great deference, bordering on awe. When we were done I asked, out of character, what that was about. Lew's reply was simple and to the point,

  "Your character can cast out demons and shoot fireballs. Every peasant in 100 miles knows who he is and what he can do. Of course they treat him with respect!"

  Let's look at those NPC numbers again and think about how PCs fit into such a low-level, low-magic world. There are only somewhere between 3 and, oh, 8 NPCs who have enough levels in magic-user to know and cast Fireball. Based upon spell availability, the chances of a mage with average Intelligence to learn a particular spell (typically on 55% for an NPC), even one as sought-after as this, and it is obvious that other than PCs there are perhaps 2 or 3 people in the entire kingdom who can cast Fireball (not counting NPCs placed by the DM).
  That means your 5th level mage is probably mentioned in gossip; at 7th level he is spoken of (usually in hushed tones) in taverns, and at 9th maybe, depending, his name is used to frighten peasant children into behaving. Your 8th level cleric? The people will have certainly heard of the patriarch and he may face strangers approaching him for blessings and healing almost everywhere he travels.
  On the other hand, there are also about 32 paladins, plus or minus, with a 5th level paladin in the mix and another as high as 10th (although that is unlikely); depending on how such things are arranged in the campaign there may be an abbey for just paladins in the kingdom. There is also at least one fighter of 8th or higher level and 8 5th level fighters - while the 5th level mage in the party is known, the fighter may be more obscure. At 9th level, however, he could very well stand out as being so famous and successful as to be elevated to the nobility.

  There is a lot more to discuss on this topic, but I hope to get some feedback before I continue.