Please forgive me if I step on any toes. This is a topic I've been playing with as well, and I wanted to share some of my results.
My Assumptions and Results
Level: Age 0-11 is level 0; age 12-13 is level 1 (apprentice); age 14-15 is level 2 (senior apprentice/journeyman); age 16-17 is level 3 (full journeyman, max skill +10, 2-3 feats); each 2 years thereafter represents a level (see CR assumptions, below).
CR: People tend to face threats in GROUPS; those best suited to facing threats are brought together to face those threats; the highest level people are highly mobile and imminently capable of finding and attacking the threats best suited to them; threats (like most ecologies) tend to rarify the higher they are, just like the population numbers. People tend to face 3-10 threats in the course of a year (of +/- 2 CRs to their level), based on the dangerousness of the D&D default worlds. The survival rate for this is pretty good (49 deaths per 1,000 people of a given age) due to organization and the fact that a CR of level+1 or lower is generally non-lethal against groups. AT AGE 13 AND LOWER, I assumed a death rate of only 5 per 1,000 people, assuming (rather optimistically) that they would generally be better protected and closer to mundane death rates (stillbirths and sickly births are ignored as part of a reduced birthrate). AT AGE 72 AND UP, adventuring STOPS; everytime I ran this, the death rate went through the roof when combined with the 2d20 roll, lost attributes (D&D's aging rules) and CR deaths combined - people who continue to fight past age 71 die quick, so the assumption is that they are reserved for emergences. This restricts levels to level 30.
Urbanization: If we assume that
plant growth is not an urban multiplier (I think it is, but that's a whole 'nother controversy
), it should at the very least result in a maximized normal urban population (as if for extremely fertile and efficient farmland). That's about 15% urbanization (150 people out of every 1,000 total population are urban). A single level 5 cleric with
plant growth with WIS 16 and the Plant Domain can, over the course of a year, cover 1,250 square miles (150,000 total population at a land density of 60). So we need seven 5th level or higher clerics per million people in the numbers below.
With a 1,000,000 population, here is the rough breakdown by level:
level 0 (0-11) - 347,512 (34.75%)
level 1 - 61,151 (6.12%)
level 2 - 56,588 (5.66%)
level 3 - 51,178 (5.12%)
level 4 - 46,285 (4.63%)
level 5 - 41,861 (4.19%)
level 6 - 37,859 (3.79%)
level 7 - 34,239 (3.42%)
level 8 - 30,966 (3.10%)
level 9 - 28,006 (2.80%)
level 10 - 25,329 (2.53%)
level 11 - 22,907 (2.29%)
level 12 - 20,717 (2.07%)
level 13 - 18,737 (1.87%)
level 14 - 16,945 (1.69%)
level 15 - 15,326 (1.53%)
level 16 - 13,860 (1.39%)
level 17 - 12,535 (1.25%)
level 18 - 11,337 (1.13%)
level 19 - 10,253 (1.03%)
level 20 - 9,273 (0.93%)
level 21 - 8,387 (0.84%)
level 22 - 7,585 (0.76%)
level 23 - 6,860 (0.69%)
level 24 - 6,204 (0.62%)
level 25 - 5,611 (0.56%)
level 26 - 5,074 (0.51%)
level 27 - 4,589 (0.46%)
level 28 - 4,151 (0.42%)
level 29 - 3,754 (0.38%)
level 30 - 3,395 (0.34%)
level 30 geezer - 31,528 (3.15%)
Class Distribution: On a 3d6 distribution, 46,296.3 people will have one attribute of 16+. Of those, 7,001.6 will have a 12+ in 2 other attributes. I'll mark that as "PC classes". Everyone else consists of "NPC classes". Here's my rough PC class ratings:
Code:
[color=skyblue] STR DEX CON INT WIS CHR Rarity Modifier
Barbarian 5 2 2 0 1 0 x0.1
Bard 0 3 0 2 0 5 x1
Cleric 0 0 2 0 5 3 x2
Druid 0 3 2 0 5 0 x0.5
Fighter 5 2 3 0 0 0 x2
Monk 3 3 0 0 4 0 x0.1
Paladin 2 1 1 0 3 3 x0.5
Ranger 2 3 2 0 3 0 x0.5
Rogue 0 4 0 3 1 2 x2
Sorcerer 0 2 1 0 0 7 x1
Wizard 0 2 1 7 0 0 x1
STR DEX CON INT WIS CHR (after rarity modifier)
Barbarian 0.5 0.2 0.2 0 0.1 0
Bard 0 3 0 2 0 5
Cleric 0 0 4 0 10 6
Druid 0 1.5 1 0 2.5 0
Fighter 10 4 6 0 0 0
Monk 0.3 0.3 0 0 0.4 0
Paladin 1 0.5 0.5 0 1.5 1.5
Ranger 1 1.5 1 0 1.5 0
Rogue 0 8 0 6 2 4
Sorcerer 0 2 1 0 0 7
Wizard 0 2 1 7 0 0[/color]
There will be roughly 1,166.7 people with a 16+ in each attribute. Using the above as a straight list of proportions for each class, I get the following numbers (and % of total population) of each:
Barbarian: 78 (0.0078%)
Bard: 556 (0.0556%)
Cleric: 1,264 (0.1263%)
Druid: 317 (0.0317%)
Fighter: 1,591 (0.1591%)
Monk: 68 (0.0068%)
Paladin: 328 (0.0328%)
Ranger: 344 (0.0344%)
Rogue: 1,201 (0.1201%)
Sorcerer: 528 (0.0528%)
Wizard: 725 (0.0725%)
That looks pretty reasonable. You can multiply that by the Population by Level chart to get how many of a particular class at a particular level, as well. Based on our level breakout, that means we have 52.9 clerics at level 5, of whom 7 need to pick up the plant domain to support the numbers we've generated. Not bad!
Applying urbanization: At 15%, the urban population is 150,000. This includes ANY specialist who does not directly contribute to agricultural production, so all PC classes are considered "urban" even if they are a Fighter who protects his farming community from attack.
Population Centers:
Largest: 30,000 (metropolis)
2nd: 15,000 (large city)
3rd: 10,000 (small city)
4th: 7,500 (small city)
5th: 6,000 (small city)
6th: 5,000 (small city/large town)
The remaining 76,500 are in towns, villages, hamlets and thorps.
