Merchant of Menace
The demographics of Sterich have been detailed down to the number of individuals of a particular race/class/alignment/level combination using the canon sources as a basis. Generally 90% of the population are commoners, warriors/aristocrats/experts make up 9% of the population and adventurers (including adepts) make up 1% of the population. NPC alignment is based upon race for non-humans and on the Sterich entry in the Living Greyhawk Gazeteer for humans.
Races that have alignments listed as Always will 100% match that alignment unless a canon source specifies otherwise for an individual or a specific campaign event alters a creatures alignment. Usually means 80% of the NPCs will have the specified alignment while Often means 40% of the NPCs will have that alignment. A crude bell curve is then used for the remainder of the NPCs of that race with more NPCs having alignments closer to the standard racial alignment. For human citizens of Sterich 40% are LG, 30% are NG, 20% are LN the remaining 10% is divided again by a crude bell curve with more people being neutral than chaotic or evil.
Levels are determined by 50% of adventurer types are level 1 or 2 with 50% of the remainder being level 2-3 etc. Warriors, Aristocrats and Experts use a scale of 50% are level 1 with 50% of the remainder being level 2 etc. Commoners use a scale of 75% are level 1 with 75% of the rmainder being level 2 etc. As a result there are 58 Legendary (Level 11+) characters in Sterich and no Epic characters.
NPCs listed in the game modules are pulled from the number in Sterich based upon their class and level. The remainder are available for PCs to use for cohorts, followers, hirelings and contacts or for the DM to flesh out as required.