| Year | Value (SE) |
|---|---|
| 2000 | 0.8720 (0.0886) |
| 2001 | 0.7490 (0.0124) |
| 2002 | 0.8580 (0.0212) |
| 2003 | 0.9110 (0.0542) |
| 2004 | 0.8330 (0.0552) |
| 2005 | 1.0410 (0.0559) |
| 2006 | 0.8990 (0.0405) |
| 2007 | 0.9690 (0.0357) |
| 2008 | 0.8930 (0.0486) |
| 2009 | 0.7480 (0.0436) |
| 2010 | 0.7710 (0.0856) |
| 2011 | 0.7370 (0.0500) |
| 2012 | 1.0190 (0.0460) |
| 2013 | 0.8810 (0.0873) |
| 2014 | 0.8490 (0.0693) |
| 2015 | 0.7410 (0.1185) |
| 2016 | 0.9280 (0.0496) |
| 2019 | 0.7740 (0.1069) |
| 2020 | 0.7660 (0.2068) |
| 2021 | 0.8440 (0.5595) |
| 2022 | 0.6590 (0.3356) |
| 2023 | 0.6860 (0.1088) |
