| Year | Value (SE) |
|---|---|
| 2000 | 0.7731 (0.0848) |
| 2001 | 0.5636 (0.0199) |
| 2002 | 0.8056 (0.0304) |
| 2003 | 0.8320 (0.0496) |
| 2004 | 0.7448 (0.0423) |
| 2005 | 0.8395 (0.0537) |
| 2006 | 0.7527 (0.0373) |
| 2007 | 0.8603 (0.0567) |
| 2008 | 0.9033 (0.1109) |
| 2009 | 0.8241 (0.0671) |
| 2010 | 0.7983 (0.1170) |
| 2011 | 0.8202 (0.1986) |
| 2012 | 0.9324 (0.0723) |
| 2013 | 0.9855 (0.1053) |
| 2014 | 0.7388 (0.0958) |
| 2015 | 0.8363 (0.2915) |
| 2016 | 0.7417 (0.0918) |
| 2018 | 0.6640 (0.1036) |
| 2019 | 0.7867 (0.1216) |
| 2020 | 0.9121 (0.2598) |
| 2021 | 0.5421 (0.4227) |
| 2022 | 1.1237 (0.5924) |
| 2023 | 0.5292 (0.1285) |
