| Year | Value (SE) |
|---|---|
| 2000 | 0.5189 (0.0696) |
| 2001 | 0.0562 (0.0125) |
| 2002 | 0.4653 (0.0547) |
| 2003 | 0.6417 (0.0856) |
| 2004 | 0.5270 (0.2022) |
| 2005 | 0.6494 (0.1506) |
| 2006 | 0.8839 (0.1235) |
| 2007 | 0.4291 (0.0812) |
| 2008 | 1.0365 (0.1377) |
| 2009 | 0.8018 (0.0862) |
| 2010 | 0.8287 (0.1249) |
| 2011 | 1.0959 (0.2198) |
| 2013 | 0.7823 (0.1636) |
| 2014 | 0.7576 (0.1823) |
| 2015 | 0.4317 (0.1059) |
| 2016 | 0.6537 (0.0834) |
| 2019 | 0.8400 (0.1634) |
| 2022 | 0.5014 (0.4134) |
| 2023 | 0.7138 (0.3129) |
