| Year | Value (SE) |
|---|---|
| 2000 | 0.8690 (0.0850) |
| 2002 | 0.9260 (0.0300) |
| 2003 | 0.8660 (0.0282) |
| 2004 | 0.7800 (0.0547) |
| 2005 | 0.8480 (0.0627) |
| 2006 | 0.9170 (0.0292) |
| 2007 | 0.9260 (0.0129) |
| 2008 | 0.9040 (0.0607) |
| 2009 | 0.7920 (0.0481) |
| 2010 | 0.9900 (0.0465) |
| 2011 | 0.8520 (0.0447) |
| 2012 | 0.7870 (0.0295) |
| 2013 | 0.8870 (0.0502) |
| 2014 | 1.0240 (0.0580) |
| 2015 | 0.6880 (0.0667) |
| 2016 | 0.8190 (0.0413) |
| 2017 | 0.6900 (0.0514) |
| 2020 | 0.8710 (0.0770) |
| 2021 | 1.0780 (0.1605) |
| 2022 | 1.1350 (0.3117) |
| 2023 | 0.9220 (0.0861) |
