| Year | Value (SE) |
|---|---|
| 2003 | 0.1640 (0.0181) |
| 2004 | 0.0910 (0.0249) |
| 2005 | 0.2950 (0.1559) |
| 2006 | 0.1690 (0.0373) |
| 2008 | 0.2640 (0.0734) |
| 2009 | 0.1220 (0.0357) |
| 2010 | 0.1600 (0.0376) |
| 2011 | 0.0910 (0.0286) |
| 2013 | 0.2830 (0.0535) |
| 2014 | 0.2990 (0.0940) |
| 2015 | 0.0430 (0.0135) |
| 2019 | 0.8060 (0.5476) |
| 2020 | 0.2610 (0.0956) |
| 2023 | 0.2720 (0.0905) |
