| Year | Value (SE) |
|---|---|
| 2000 | 0.4598 (0.0625) |
| 2001 | 0.0362 (0.0081) |
| 2002 | 0.4979 (0.0592) |
| 2003 | 0.6430 (0.0866) |
| 2004 | 0.4664 (0.1790) |
| 2005 | 0.5637 (0.1307) |
| 2006 | 0.7177 (0.1010) |
| 2007 | 0.4042 (0.0775) |
| 2008 | 1.0478 (0.1410) |
| 2009 | 0.7336 (0.0800) |
| 2010 | 0.6680 (0.1045) |
| 2011 | 1.0236 (0.2071) |
| 2013 | 0.7838 (0.1666) |
| 2014 | 0.8174 (0.1998) |
| 2015 | 0.3820 (0.0975) |
| 2016 | 0.5681 (0.0745) |
| 2019 | 0.8114 (0.1594) |
| 2022 | 0.6433 (0.5405) |
| 2023 | 0.9058 (0.4070) |
