| Year | Value (SE) |
|---|---|
| 2000 | 0.7726 (0.1488) |
| 2001 | 0.6359 (0.0382) |
| 2002 | 0.7173 (0.0389) |
| 2003 | 0.9338 (0.0761) |
| 2004 | 0.7655 (0.1065) |
| 2005 | 0.8338 (0.1093) |
| 2006 | 0.7830 (0.0711) |
| 2007 | 0.9322 (0.0469) |
| 2008 | 0.9993 (0.1119) |
| 2009 | 0.5326 (0.0556) |
| 2010 | 0.7679 (0.1143) |
| 2011 | 0.6272 (0.0811) |
| 2012 | 0.8284 (0.0607) |
| 2013 | 0.7674 (0.1137) |
| 2014 | 0.7463 (0.1010) |
| 2015 | 0.4446 (0.0942) |
| 2016 | 0.6719 (0.0693) |
| 2019 | 0.6316 (0.1101) |
| 2020 | 0.6741 (0.1995) |
| 2021 | 0.8862 (0.6491) |
| 2022 | 0.3565 (0.1997) |
| 2023 | 0.5735 (0.1092) |
