| Year | Value (SE) |
|---|---|
| 2000 | 0.9580 (0.1800) |
| 2001 | 0.6620 (0.0192) |
| 2002 | 0.8080 (0.0360) |
| 2003 | 1.0790 (0.0838) |
| 2004 | 0.8940 (0.0830) |
| 2005 | 1.0340 (0.0785) |
| 2006 | 0.9360 (0.0757) |
| 2007 | 0.9050 (0.0518) |
| 2008 | 0.8940 (0.0782) |
| 2009 | 0.7800 (0.0529) |
| 2010 | 0.7600 (0.1063) |
| 2011 | 0.7950 (0.0799) |
| 2012 | 1.0250 (0.0737) |
| 2013 | 0.9930 (0.1172) |
| 2014 | 0.8270 (0.0743) |
| 2015 | 0.8290 (0.1809) |
| 2016 | 0.9700 (0.0624) |
| 2019 | 0.9660 (0.1317) |
| 2020 | 0.6780 (0.1498) |
| 2021 | 0.3270 (0.3191) |
| 2022 | 0.6710 (0.1654) |
| 2023 | 1.0310 (0.1669) |
