| Year | Value (SE) |
|---|---|
| 2000 | 0.8860 (0.0381) |
| 2001 | 0.6440 (0.0344) |
| 2002 | 1.0700 (0.0392) |
| 2003 | 1.0020 (0.0417) |
| 2004 | 0.8850 (0.0341) |
| 2005 | 0.8680 (0.0211) |
| 2006 | 0.8120 (0.0234) |
| 2007 | 0.9420 (0.0693) |
| 2008 | 1.0110 (0.0588) |
| 2009 | 0.9150 (0.0328) |
| 2010 | 0.8060 (0.0838) |
| 2011 | 0.9340 (0.0489) |
| 2013 | 1.0020 (0.0887) |
| 2014 | 1.0790 (0.1166) |
| 2015 | 0.8850 (0.1507) |
| 2016 | 0.8690 (0.0479) |
| 2019 | 0.9660 (0.0593) |
| 2022 | 1.2830 (0.4027) |
| 2023 | 1.2690 (0.2338) |
