| Year | Value (SE) |
|---|---|
| 2000 | 0.6300 (0.0862) |
| 2001 | 0.7990 (0.0440) |
| 2002 | 0.9420 (0.0661) |
| 2003 | 0.8370 (0.0862) |
| 2004 | 0.9260 (0.1270) |
| 2007 | 0.9480 (0.0542) |
| 2010 | 0.8570 (0.0678) |
| 2011 | 0.8320 (0.0752) |
| 2012 | 0.8630 (0.0566) |
| 2013 | 0.8450 (0.0718) |
| 2014 | 0.8630 (0.0787) |
| 2015 | 0.8830 (0.1492) |
| 2016 | 0.9280 (0.0636) |
| 2017 | 0.9270 (0.0859) |
| 2018 | 0.8880 (0.0651) |
| 2022 | 0.3680 (0.1542) |
| 2023 | 0.5850 (0.0984) |
| 2024 | 0.7310 (0.2214) |
