| Year | Value (SE) |
|---|---|
| 2000 | 0.6949 (0.0381) |
| 2002 | 0.7344 (0.0172) |
| 2003 | 0.8061 (0.0271) |
| 2004 | 0.6928 (0.0274) |
| 2005 | 0.7952 (0.0220) |
| 2006 | 0.6534 (0.0132) |
| 2007 | 0.8118 (0.0154) |
| 2008 | 0.7200 (0.0329) |
| 2009 | 0.7773 (0.0299) |
| 2010 | 0.8722 (0.0566) |
| 2011 | 0.7090 (0.0200) |
| 2012 | 0.8549 (0.0258) |
| 2013 | 0.8376 (0.0433) |
| 2014 | 0.8406 (0.0367) |
| 2015 | 0.7886 (0.0878) |
| 2016 | 0.7542 (0.0287) |
| 2017 | 0.4346 (0.0259) |
| 2020 | 0.7150 (0.1688) |
| 2021 | 0.6880 (0.3077) |
| 2022 | 0.5223 (0.1900) |
| 2023 | 0.5977 (0.0670) |
