| Year | Value (SE) |
|---|---|
| 2000 | 0.3214 (0.0440) |
| 2001 | 0.0258 (0.0058) |
| 2002 | 0.4590 (0.0551) |
| 2003 | 0.5851 (0.0794) |
| 2004 | 0.4132 (0.1586) |
| 2005 | 0.5298 (0.1229) |
| 2006 | 0.6962 (0.0984) |
| 2007 | 0.3468 (0.0671) |
| 2008 | 0.9577 (0.1303) |
| 2009 | 0.7050 (0.0773) |
| 2010 | 0.6586 (0.1049) |
| 2011 | 0.9806 (0.1992) |
| 2013 | 0.7305 (0.1573) |
| 2014 | 0.7978 (0.1963) |
| 2015 | 0.4523 (0.1178) |
| 2016 | 0.5584 (0.0738) |
| 2019 | 0.7384 (0.1466) |
| 2022 | 0.5758 (0.4839) |
| 2023 | 0.6649 (0.2995) |
