| Year | Value (SE) |
|---|---|
| 2000 | 0.8807 (0.0906) |
| 2001 | 0.6704 (0.0117) |
| 2002 | 0.8142 (0.0241) |
| 2003 | 0.8281 (0.0532) |
| 2004 | 0.7564 (0.0507) |
| 2005 | 0.9046 (0.0493) |
| 2006 | 0.8307 (0.0385) |
| 2007 | 0.9419 (0.0411) |
| 2008 | 0.7894 (0.0460) |
| 2009 | 0.8138 (0.0512) |
| 2010 | 0.7872 (0.0956) |
| 2011 | 0.7834 (0.0551) |
| 2012 | 0.9528 (0.0449) |
| 2013 | 0.9083 (0.1012) |
| 2014 | 0.7548 (0.0660) |
| 2015 | 0.7884 (0.1405) |
| 2016 | 0.7888 (0.0459) |
| 2019 | 0.8019 (0.1197) |
| 2020 | 0.8801 (0.2733) |
| 2021 | 1.1318 (0.8523) |
| 2022 | 0.8119 (0.4295) |
| 2023 | 0.6222 (0.1051) |
