| Year | Value (SE) |
|---|---|
| 2000 | 0.8333 (0.0371) |
| 2002 | 0.9056 (0.0184) |
| 2003 | 0.8217 (0.0247) |
| 2004 | 0.8905 (0.0278) |
| 2005 | 0.8215 (0.0122) |
| 2006 | 0.7580 (0.0107) |
| 2007 | 0.8891 (0.0158) |
| 2008 | 0.7912 (0.0271) |
| 2009 | 0.9741 (0.0323) |
| 2010 | 0.9585 (0.0600) |
| 2011 | 0.8829 (0.0178) |
| 2012 | 0.8050 (0.0172) |
| 2013 | 0.9808 (0.0458) |
| 2014 | 0.8991 (0.0316) |
| 2015 | 1.1154 (0.1184) |
| 2016 | 0.8084 (0.0231) |
| 2017 | 0.5601 (0.0228) |
| 2020 | 1.0899 (0.2481) |
| 2021 | 0.8809 (0.3879) |
| 2022 | 0.8705 (0.2646) |
| 2023 | 0.8034 (0.0682) |
