Data Table
| Year | Value (SE) |
| 2000 | 1.0250 (0.0652) |
| 2001 | 0.6470 (0.0193) |
| 2002 | 0.8750 (0.0613) |
| 2003 | 1.0330 (0.0518) |
| 2004 | 0.7820 (0.0879) |
| 2005 | 0.9280 (0.0239) |
| 2006 | 0.9540 (0.0415) |
| 2007 | 0.8650 (0.0238) |
| 2008 | 0.8080 (0.0360) |
| 2009 | 0.7310 (0.0282) |
| 2010 | 0.8020 (0.0626) |
| 2011 | 0.7410 (0.0321) |
| 2012 | 1.1190 (0.0313) |
| 2013 | 0.8600 (0.0440) |
| 2014 | 0.8100 (0.0353) |
| 2015 | 0.9010 (0.0960) |
| 2016 | 0.9510 (0.0378) |
| 2017 | 0.8830 (0.0478) |
| 2018 | 0.8060 (0.0558) |
| 2019 | 0.9250 (0.0649) |
| 2020 | 1.0120 (0.1114) |
| 2021 | 0.8620 (0.3030) |
| 2022 | 0.7890 (0.1369) |
| 2023 | 0.7130 (0.0657) |
| 2024 | 0.8380 (0.3963) |