| Year | Return to scale coefficient | Type |
| 2017 | 1.000 | Fixed returns to scale |
| 2018 | 0.973 | Diminishing returns to scale |
| 2019 | 0.997 | Diminishing returns to scale |
| 2020 | 0.996 | Diminishing returns to scale |
| 2021 | 1.000 | Fixed returns to scale |