Data Table
| Year | Value (SE) |
| 2000 | 1.2730 (0.2731) |
| 2001 | 0.9490 (0.0963) |
| 2002 | 0.9400 (0.1546) |
| 2003 | 0.9110 (0.0508) |
| 2004 | 0.8700 (0.1711) |
| 2005 | 0.8530 (0.0675) |
| 2006 | 0.8050 (0.0597) |
| 2007 | 1.0190 (0.0233) |
| 2008 | 1.1070 (0.0843) |
| 2009 | 0.8810 (0.0698) |
| 2010 | 0.9700 (0.0719) |
| 2011 | 1.1290 (0.1072) |
| 2012 | 0.8470 (0.0348) |
| 2013 | 1.0200 (0.0719) |
| 2014 | 1.0600 (0.0690) |
| 2015 | 0.8240 (0.0598) |
| 2016 | 0.7890 (0.0534) |
| 2017 | 0.9560 (0.0607) |
| 2018 | 0.8580 (0.0739) |
| 2019 | 0.7580 (0.0565) |
| 2020 | 0.9230 (0.0770) |
| 2021 | 0.9800 (0.1271) |
| 2022 | 1.1120 (0.2100) |
| 2023 | 0.9910 (0.0980) |
| 2024 | 0.8180 (0.1220) |