| Year | Value (SE) |
|---|---|
| 2000 | 0.6883 (0.0304) |
| 2002 | 0.7426 (0.0148) |
| 2003 | 0.5785 (0.0173) |
| 2004 | 0.7560 (0.0235) |
| 2005 | 0.6835 (0.0101) |
| 2006 | 0.6450 (0.0090) |
| 2007 | 0.7255 (0.0128) |
| 2008 | 0.5831 (0.0198) |
| 2009 | 0.6751 (0.0223) |
| 2010 | 0.8559 (0.0533) |
| 2011 | 0.6384 (0.0129) |
| 2012 | 0.5989 (0.0129) |
| 2013 | 0.7778 (0.0361) |
| 2014 | 0.7336 (0.0257) |
| 2015 | 0.8577 (0.0911) |
| 2016 | 0.5772 (0.0166) |
| 2017 | 0.3663 (0.0150) |
| 2020 | 0.8883 (0.2022) |
| 2021 | 0.6924 (0.3049) |
| 2022 | 0.7747 (0.2355) |
| 2023 | 0.6580 (0.0558) |
