| Year | Value (SE) |
|---|---|
| 2000 | 0.6827 (0.0761) |
| 2001 | 0.5354 (0.0191) |
| 2002 | 0.7572 (0.0303) |
| 2003 | 0.7588 (0.0468) |
| 2004 | 0.7321 (0.0417) |
| 2005 | 0.7849 (0.0504) |
| 2006 | 0.6684 (0.0347) |
| 2007 | 0.8112 (0.0560) |
| 2008 | 0.8518 (0.1065) |
| 2009 | 0.7837 (0.0657) |
| 2010 | 0.7608 (0.1161) |
| 2011 | 0.8120 (0.1990) |
| 2012 | 0.8010 (0.0651) |
| 2013 | 0.9668 (0.1051) |
| 2014 | 0.7942 (0.1048) |
| 2015 | 0.8113 (0.2939) |
| 2016 | 0.7143 (0.0899) |
| 2018 | 0.7038 (0.1107) |
| 2019 | 0.7379 (0.1173) |
| 2020 | 0.7999 (0.2315) |
| 2021 | 0.5908 (0.4616) |
| 2022 | 0.8428 (0.4462) |
| 2023 | 0.5577 (0.1364) |
