| PTEs | 2015 | 2016 | 2017 | 2018 | 2019 | |||||
| Quantities (piece) | Proportions (%) | Quantities (piece) | Proportions (%) | Quantities (piece) | Proportions (%) | Quantities (piece) | Proportions (%) | Quantities (piece) | Proportions (%) | |
| 1 | 181 | 94.27 | 175 | 91.15 | 174 | 90.63 | 174 | 90.63 | 177 | 92.19 |
| [0.8, 1) | 10 | 5.21 | 16 | 8.33 | 16 | 8.33 | 17 | 8.85 | 13 | 6.77 |
| [0.5, 0.8) | 1 | 0.52 | 1 | 0.52 | 2 | 1.04 | 1 | 0.52 | 2 | 1.04 |
| (0, 0.5) | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 |