| Year | Value (SE) |
|---|---|
| 2000 | 0.3080 (0.0331) |
| 2001 | 0.0200 (0.0037) |
| 2002 | 0.4090 (0.0409) |
| 2003 | 0.5430 (0.0575) |
| 2004 | 0.3900 (0.1392) |
| 2005 | 0.5110 (0.1095) |
| 2006 | 0.6390 (0.0786) |
| 2007 | 0.3480 (0.0415) |
| 2008 | 0.9580 (0.0969) |
| 2009 | 0.7000 (0.0637) |
| 2010 | 0.6590 (0.0647) |
| 2011 | 0.9620 (0.1658) |
| 2013 | 0.7050 (0.1151) |
| 2014 | 0.8070 (0.1550) |
| 2015 | 0.3890 (0.0638) |
| 2016 | 0.5470 (0.0524) |
| 2019 | 0.7130 (0.1058) |
| 2022 | 0.5370 (0.1985) |
| 2023 | 0.6270 (0.1334) |
