| O & M | I & S | TOTAL RATE | |
| 2025 | 0.23355 | 0.1180 | 0.3535 |
| 2024 | 0.2623 | 0.1159 | 0.3782 |
| 2023 | 0.2922 | 0.1361 | 0.4283 |
| 2022 | 0.3174 | 0.1598 | 0.4772 |
| 2021 | 0.3270 | 0.2000 | 0.5270 |
| 2020 | 0.3217 | 0.1843 | 0.5060 |
| 2019 | 0.2930 | 0.1780 | 0.4710 |
| 2018 | 0.2561 | 0.1989 | 0.4550 |
| 2017 | 0.2467 | 0.1993 | 0.4460 |
