| Year | Value (SE) |
|---|---|
| 2003 | 0.6638 (0.1138) |
| 2004 | 0.3187 (0.1032) |
| 2005 | 0.8469 (0.4602) |
| 2006 | 1.0385 (0.2796) |
| 2008 | 0.7647 (0.2972) |
| 2009 | 0.3927 (0.1516) |
| 2010 | 0.4985 (0.1578) |
| 2011 | 0.3458 (0.1419) |
| 2013 | 0.5113 (0.1448) |
| 2014 | 0.6018 (0.2412) |
| 2015 | 0.2116 (0.1273) |
| 2019 | 1.6440 (1.2464) |
| 2020 | 0.4203 (0.3411) |
| 2023 | 0.5114 (0.3582) |
