| Year | Value (SE) |
|---|---|
| 2000 | 0.8250 (0.1691) |
| 2001 | 0.5108 (0.0158) |
| 2002 | 0.7759 (0.0411) |
| 2003 | 0.9023 (0.0808) |
| 2004 | 0.7600 (0.0720) |
| 2005 | 0.8459 (0.0658) |
| 2006 | 0.7938 (0.0684) |
| 2007 | 0.8385 (0.0580) |
| 2008 | 0.8236 (0.0756) |
| 2009 | 0.8088 (0.0602) |
| 2010 | 0.8257 (0.1302) |
| 2011 | 0.7618 (0.0818) |
| 2012 | 0.8125 (0.0638) |
| 2013 | 0.9431 (0.1211) |
| 2014 | 0.7977 (0.0774) |
| 2015 | 0.8923 (0.2217) |
| 2016 | 0.8097 (0.0581) |
| 2019 | 0.8673 (0.1334) |
| 2020 | 0.7791 (0.1860) |
| 2021 | 0.6019 (0.6511) |
| 2022 | 0.5357 (0.1480) |
| 2023 | 0.8902 (0.1600) |
