Data Table
| Year | Value (SE) |
| 2000 | 0.4140 (0.2602) |
| 2001 | 0.5510 (0.0668) |
| 2002 | 0.8640 (0.1158) |
| 2003 | 1.0250 (0.2065) |
| 2004 | 1.1110 (0.3535) |
| 2005 | 1.0230 (0.3220) |
| 2006 | 0.7340 (0.1281) |
| 2007 | 0.6890 (0.1282) |
| 2008 | 0.9140 (0.2318) |
| 2009 | 0.7780 (0.1727) |
| 2010 | 0.7270 (0.1600) |
| 2011 | 0.6010 (0.1552) |
| 2012 | 0.9210 (0.0568) |
| 2013 | 0.8340 (0.0766) |
| 2014 | 0.6750 (0.0350) |
| 2015 | 0.4840 (0.0560) |
| 2016 | 0.3450 (0.0254) |
| 2017 | 0.7840 (0.0682) |
| 2018 | 0.7590 (0.0773) |
| 2019 | 0.7980 (0.0906) |
| 2021 | 0.8330 (0.0928) |
| 2022 | 0.6050 (0.0597) |
| 2023 | 0.2940 (0.0511) |
| 2024 | 0.5250 (0.1000) |