S&P Credit rating history
| Date | Agency | Rating Type | Rating | Action |
| 09/07/2025 | S & P | LT Issuer | A- | Rating Affirmed |
| 07/02/2024 | S & P | LT Issuer | A- | Rating Affirmed |
| 07/02/2024 | S & P | LT Issuer | A- | Rating Affirmed |
| 22/6/2023 | S & P | LT Issuer | A- | Rating Affirmed |
| 22/6/2023 | S & P | LT Issuer | A- | Rating Affirmed |
| 22/6/2022 | S & P | LT Issuer | A- | Rating Affirmed |
| 22/6/2022 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 24/6/2021 | S & P | LT Issuer | A- | Rating Affirmed |
| 24/6/2021 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 26/6/2020 | S & P | LT Issuer | A- | Rating Affirmed |
| 26/6/2020 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 09/09/2019 | S & P | LT Issuer | A- | Rating Downgraded |
| 09/09/2019 | S & P | ST Issuer | A-2 | Rating Downgraded |
| 11/07/2018 | S & P | ST Issuer | A-1 | Rating Affirmed |
| 02/06/2017 | S & P | LT Issuer | A | Rating Affirmed |
| 02/06/2017 | S & P | ST Issuer | A-1 | Rating Affirmed |
| 23/06/2016 | S & P | LT Issuer | A | Rating Affirmed |
| 23/06/2016 | S & P | ST Issuer | A-1 | Rating Affirmed |
| 19/11/2014 | S & P | LT Issuer | A | Rating Upgrade |
| 19/11/2014 | S & P | ST Issuer | A-1 | Rating Upgrade |
| 17/10/2013 | S & P | LT Issuer | A- | Rating Affirmed - Positive Outlook |
| 17/10/2013 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 29/04/2013 | S & P | LT Issuer | A- | Rating Affirmed |
| 29/04/2013 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 15/10/2012 | S & P | LT Issuer | A- | Rating Affirmed |
| 15/10/2012 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 27/04/2012 | S & P | LT Issuer | A- | Rating Affirmed |
| 27/04/2012 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 05/04/2011 | S & P | LT Issuer | A- | Rating Affirmed |
| 05/04/2011 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 12/04/2010 | S & P | LT Issuer | A- | Rating Affirmed |
| 10/02/2010 | S & P | LT Issuer | A- | CreditWatch with negative implications |
| 30/06/2009 | S & P | LT Issuer | A- | Rating Upgrade |
| 30/06/2009 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 28/01/2009 | S & P | LT Issuer | BBB+ | Rating Affirmed |
| 28/01/2009 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 30/10/2008 | S & P | LT Issuer | BBB+ | Rating Affirmed |
| 30/10/2008 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 01/08/2006 | S & P | LT Issuer | BBB+ | Rating Downgraded |
| 01/08/2006 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 01/11/2005 | S & P | LT Issuer | A- | Rating Affirmed |
| 01/11/2005 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 21/10/2005 | S & P | LT Issuer | A- | Rating Affirmed |
| 21/10/2005 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 13/09/2004 | S & P | LT Issuer | A- | Rating Affirmed |
| 13/09/2004 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 13/03/2003 | S & P | LT Issuer | A- | Rating Affirmed |
| 13/03/2003 | S & P | ST Issuer | A-2 | Rating Affirmed |
| 13/03/2002 | S & P | LT Issuer | A- | New Rating |
| 13/03/2002 | S & P | ST Issuer | A-2 | New Rating |
| 25/09/2001 | S & P | LT Issuer | A- | Rating Downgraded |
| 25/09/2001 | S & P | LT Issuer | Rating Off Watch | |
| 25/09/2001 | S & P | ST Issuer | A-2 | Rating Downgraded |
| 25/09/2001 | S & P | ST Issuer | Rating Off Watch | |
| 26/07/2001 | S & P | LT Issuer | A | Rating On Watch Down |
| 26/07/2001 | S & P | ST Issuer | A-1 | Rating On Watch Down |
| 16/01/2001 | S & P | LT Issuer | A | Rating Downgraded |
| 16/01/2001 | S & P | LT Issuer | Rating Off Watch | |
| 16/01/2001 | S & P | ST Issuer | A-1 | Rating Downgraded |
| 16/01/2001 | S & P | ST Issuer | Rating Off Watch | |
| 13/06/2000 | S & P | ST Issuer | A-1+ | Rating On Watch Down |
| 03/04/2000 | S & P | LT Issuer | AA | Rating Downgraded |
| 03/04/2000 | S & P | LT Issuer | Rating Off Watch |