I've also run an unofficial census based off of the character sheets.

Nations of Osetia by population:

1. Avalia: 147,780,900
2. Yllendthyr: 142,650,202
3. Tiqsimuyu: 126,547,467
4. Tin: 125,000,000
5. KalMea: 100,340,000
6. Kataylabinsk: 77,110,000
7. Ventium: 75,950,000
8. Yamatai: 75,000,000
9. Eisenkreis: 53,258,333
10. Dong Wei: 52,000,000
11. Umbraisis: 30,000,000 (unconfirmed)
12. Hambria: 15,000,001

Approximate Total World Population: 1,020,000,000