| Epoch I | Epoch II | Epoch III | Epoch IV | Epoch V | Epoch VI | Epoch VII | Epoch VIII | |
| Middle East | 4 | 4 | 4 | 4 | 4 | 3 | 3 | 4 |
| North Africa | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 |
| China | 3 | 4 | 5 | 6 | 5 | 5 | 6 | 7 |
| India | 1 | 3 | 4 | 5 | 5 | 5 | 6 | 7 |
| Southern Europe | 2 | 3 | 4 | 4 | 4 | 4 | 4 | 6 |
| Northern Europe | 2 | 2 | 3 | 3 | 3 | 5 | 6 | 8 |
| Southeast Asia | 1 | 1 | 1 | 2 | 3 | 3 | 4 | 5 |
| Eurasia | 1 | 1 | 1 | 2 | 2 | 2 | 2 | 4 |
| North America | 1 | 1 | 1 | 2 | 3 | 3 | 3 | 5 |
| South America | 1 | 1 | 1 | 1 | 2 | 3 | 3 | 3 |
| Subsaharan Africa | 1 | 1 | 1 | 2 | 3 | 3 | 4 | 5 |
| Japan | 1 | 2 | 3 | 4 | 5 | |||
| Australia | 1 | 1 |