| Year | Value (SE) |
|---|---|
| 2000 | 0.4184 (0.0360) |
| 2001 | 0.1317 (0.0183) |
| 2002 | 0.4685 (0.0318) |
| 2003 | 0.5870 (0.0502) |
| 2004 | 0.3893 (0.0553) |
| 2005 | 0.6826 (0.0609) |
| 2006 | 0.5504 (0.0396) |
| 2007 | 0.7896 (0.1205) |
| 2008 | 0.7245 (0.0662) |
| 2009 | 0.7377 (0.0457) |
| 2010 | 0.7367 (0.0926) |
| 2011 | 0.6685 (0.0726) |
| 2013 | 0.6167 (0.0868) |
| 2014 | 0.6490 (0.1000) |
| 2015 | 0.6885 (0.1395) |
| 2016 | 0.7410 (0.0677) |
| 2019 | 0.4979 (0.0675) |
| 2022 | 1.8524 (1.3988) |
| 2023 | 0.5876 (0.2336) |
