| Year | Value (SE) |
|---|---|
| 2000 | 0.6039 (0.0658) |
| 2002 | 0.6801 (0.0261) |
| 2003 | 0.6981 (0.0312) |
| 2004 | 0.5404 (0.0416) |
| 2005 | 0.6743 (0.0509) |
| 2006 | 0.5991 (0.0210) |
| 2007 | 0.7517 (0.0170) |
| 2008 | 0.6508 (0.0493) |
| 2009 | 0.6157 (0.0428) |
| 2010 | 0.8635 (0.0677) |
| 2011 | 0.6041 (0.0341) |
| 2012 | 0.6728 (0.0292) |
| 2013 | 0.7430 (0.0547) |
| 2014 | 0.8608 (0.0579) |
| 2015 | 0.5425 (0.0783) |
| 2016 | 0.6177 (0.0361) |
| 2017 | 0.2999 (0.0257) |
| 2020 | 0.6227 (0.1525) |
| 2021 | 0.7416 (0.3452) |
| 2022 | 0.5928 (0.2437) |
| 2023 | 0.5511 (0.0703) |
