| Year | Value (SE) |
|---|---|
| 2000 | 0.7912 (0.2565) |
| 2001 | 0.4786 (0.0569) |
| 2002 | 0.9602 (0.0950) |
| 2003 | 0.6791 (0.0616) |
| 2004 | 0.7768 (0.1114) |
| 2005 | 0.5596 (0.0867) |
| 2006 | 0.5902 (0.0582) |
| 2007 | 0.6571 (0.0580) |
| 2008 | 0.7718 (0.1683) |
| 2009 | 0.5557 (0.0922) |
| 2010 | 0.9966 (0.2719) |
| 2011 | 0.2972 (0.0974) |
| 2012 | 0.4974 (0.0580) |
| 2013 | 0.6361 (0.1124) |
| 2014 | 0.7259 (0.1647) |
| 2015 | 0.4259 (0.2014) |
| 2016 | 0.5771 (0.1398) |
| 2018 | 0.6088 (0.1465) |
| 2019 | 0.8043 (0.1814) |
| 2020 | 0.5919 (0.1986) |
| 2021 | 0.3905 (0.3356) |
| 2022 | 0.7400 (0.4846) |
| 2023 | 0.6905 (0.2284) |
