| Year | Value (SE) |
|---|---|
| 2000 | 0.4372 (0.0376) |
| 2001 | 0.1674 (0.0232) |
| 2002 | 0.5258 (0.0356) |
| 2003 | 0.6319 (0.0540) |
| 2004 | 0.4132 (0.0586) |
| 2005 | 0.7074 (0.0631) |
| 2006 | 0.6002 (0.0431) |
| 2007 | 0.7864 (0.1201) |
| 2008 | 0.7245 (0.0663) |
| 2009 | 0.7421 (0.0459) |
| 2010 | 0.7367 (0.0926) |
| 2011 | 0.6800 (0.0738) |
| 2013 | 0.6397 (0.0901) |
| 2014 | 0.6413 (0.0989) |
| 2015 | 0.8005 (0.1622) |
| 2016 | 0.7577 (0.0692) |
| 2019 | 0.5160 (0.0699) |
| 2022 | 1.9854 (1.4993) |
| 2023 | 0.6231 (0.2477) |
