| Company | Ranking | Outlook | Date |
|---|---|---|---|
| Fitch | AAA | Secure | Jul 08 2022 |
| Fitch | AAA | Unfavorable | Jul 31 2020 |
| DBRS | AAA | Secure | Apr 22 2014 |
| Fitch | AAA | Secure | Mar 21 2014 |
| Fitch | AAA | Unfavorable Watch | Oct 15 2013 |
| DBRS | AAA | Below Overview | Oct 09 2013 |
| Moody’s | Aaa | Secure | Jul 18 2013 |
| S&P | AA+ | Secure | Jun 10 2013 |
| Fitch | AAA | Unfavorable | Nov 28 2011 |
| DBRS | AAA | Secure | Sep 08 2011 |
| S&P | AA+ | Unfavorable | Aug 05 2011 |
| Moody’s | Aaa | Unfavorable | Aug 02 2011 |
| S&P | AAA | Unfavorable Watch | Jul 14 2011 |
| Moody’s | Aaa | Unfavorable Watch | Jul 13 2011 |
| S&P | AAA | Unfavorable | Apr 18 2011 |
| Fitch | AAA | Secure | Sep 21 2000 |
| Fitch | AAA | N/A | Apr 01 1996 |
| Fitch | AAA | Unfavorable Watch | Nov 13 1995 |
| Fitch | AAA | N/A | Aug 10 1994 |
| Moody’s | Aaa | Secure | Feb 05 1949 |
