| Between regions | Regional contribution rate | within the area | Contribution rate within the region | Global differentiation index |
Differentiation index in 2017 | 0.224 | 0.678 | 0.106 | 0.321 | 0.330 |
Differentiation index in 2018 | 0.251 | 0.733 | 0.096 | 0.276 | 0.347 |
Differentiation index in 2019 | 0.256 | 0.741 | 0.089 | 0.258 | 0.345 |