Credit Ratings
| Year | Rating Agency | Credit Rating | Rating Outlook | |
| Long-term | Short-term | |||
| 2023 | FITCH IBCA | AA+(twn) | F1+(twn) | Stable |
| 2022 | FITCH IBCA | AA+(twn) | F1+(twn) | Stable |
| 2021 | FITCH IBCA | AA+(twn) | F1+(twn) | Stable |
| 2020 | FITCH IBCA | AA+(twn) | F1+(twn) | Stable |
| 2019 | FITCH IBCA | AA+(twn) | F1+(twn) | Stable |
| 2018 | FITCH IBCA | AA+(twn) | F1+(twn) | Stable |
| 2017 | FITCH IBCA | AA+(twn) | F1+(twn) | Stable |
| 2016 | FITCH IBCA | AA(twn) | F1+(twn) | Stable |
| 2015 | FITCH IBCA | AA(twn) | F1+(twn) | Stable |