| Year | Value (SE) |
|---|---|
| 2000 | 0.6689 (0.0187) |
| 2001 | 0.5603 (0.0126) |
| 2002 | 0.8215 (0.0205) |
| 2003 | 0.8454 (0.0212) |
| 2004 | 0.8346 (0.0071) |
| 2005 | 0.9071 (0.0066) |
| 2006 | 0.8895 (0.0174) |
| 2007 | 0.8614 (0.0359) |
| 2008 | 0.9140 (0.0270) |
| 2009 | 0.9552 (0.0199) |
| 2010 | 0.9860 (0.0503) |
| 2011 | 0.9417 (0.0301) |
| 2013 | 0.8984 (0.0459) |
| 2014 | 0.9877 (0.0510) |
| 2015 | 1.0182 (0.0887) |
| 2016 | 0.9614 (0.0327) |
| 2019 | 0.8781 (0.0354) |
| 2022 | 0.8350 (0.1364) |
| 2023 | 0.6922 (0.0726) |
