| Year | Value (SE) |
|---|---|
| 2000 | 0.8590 (0.0458) |
| 2002 | 0.7940 (0.0146) |
| 2003 | 0.8849 (0.0279) |
| 2004 | 0.7539 (0.0296) |
| 2005 | 0.8615 (0.0237) |
| 2006 | 0.8017 (0.0143) |
| 2007 | 0.8710 (0.0147) |
| 2008 | 0.8035 (0.0348) |
| 2009 | 0.7820 (0.0293) |
| 2010 | 0.9318 (0.0575) |
| 2011 | 0.7757 (0.0209) |
| 2012 | 0.9940 (0.0281) |
| 2013 | 0.8591 (0.0411) |
| 2014 | 0.8639 (0.0365) |
| 2015 | 0.7671 (0.0841) |
| 2016 | 0.8024 (0.0303) |
| 2017 | 0.6130 (0.0343) |
| 2020 | 0.7944 (0.1875) |
| 2021 | 0.7748 (0.3466) |
| 2022 | 0.7194 (0.2619) |
| 2023 | 0.6220 (0.0697) |
