| Year | Value (SE) |
|---|---|
| 2000 | 0.7803 (0.1508) |
| 2001 | 0.5691 (0.0343) |
| 2002 | 0.6807 (0.0386) |
| 2003 | 0.8488 (0.0722) |
| 2004 | 0.6951 (0.0969) |
| 2005 | 0.7246 (0.0952) |
| 2006 | 0.7235 (0.0661) |
| 2007 | 0.9061 (0.0502) |
| 2008 | 0.8834 (0.1006) |
| 2009 | 0.5794 (0.0620) |
| 2010 | 0.7840 (0.1229) |
| 2011 | 0.6667 (0.0871) |
| 2012 | 0.7746 (0.0577) |
| 2013 | 0.7911 (0.1239) |
| 2014 | 0.6634 (0.0922) |
| 2015 | 0.4731 (0.1070) |
| 2016 | 0.5711 (0.0603) |
| 2019 | 0.6543 (0.1200) |
| 2020 | 0.7745 (0.2581) |
| 2021 | 1.1884 (0.9684) |
| 2022 | 0.4392 (0.2539) |
| 2023 | 0.5202 (0.1036) |
