| Year | Value (SE) |
|---|---|
| 2000 | 0.7247 (0.0783) |
| 2002 | 0.7510 (0.0251) |
| 2003 | 0.8495 (0.0347) |
| 2004 | 0.6068 (0.0466) |
| 2005 | 0.8209 (0.0618) |
| 2006 | 0.7905 (0.0263) |
| 2007 | 0.8454 (0.0158) |
| 2008 | 0.8226 (0.0592) |
| 2009 | 0.6320 (0.0423) |
| 2010 | 0.9009 (0.0658) |
| 2011 | 0.6842 (0.0377) |
| 2012 | 0.8358 (0.0344) |
| 2013 | 0.7575 (0.0515) |
| 2014 | 0.9574 (0.0618) |
| 2015 | 0.4864 (0.0652) |
| 2016 | 0.7641 (0.0423) |
| 2017 | 0.5354 (0.0436) |
| 2020 | 0.5714 (0.1286) |
| 2021 | 0.8419 (0.3413) |
| 2022 | 0.6810 (0.2547) |
| 2023 | 0.6860 (0.0794) |
