| Year | Value (SE) |
|---|---|
| 2000 | 1.0300 (0.0440) |
| 2002 | 0.9790 (0.0140) |
| 2003 | 0.9020 (0.0250) |
| 2004 | 0.9690 (0.0299) |
| 2005 | 0.8900 (0.0128) |
| 2006 | 0.9300 (0.0099) |
| 2007 | 0.9540 (0.0148) |
| 2008 | 0.8830 (0.0274) |
| 2009 | 0.9800 (0.0314) |
| 2010 | 1.0240 (0.0607) |
| 2011 | 0.9660 (0.0176) |
| 2012 | 0.9360 (0.0174) |
| 2013 | 1.0060 (0.0428) |
| 2014 | 0.9240 (0.0308) |
| 2015 | 1.0850 (0.1132) |
| 2016 | 0.8600 (0.0241) |
| 2017 | 0.7900 (0.0278) |
| 2020 | 1.2110 (0.2756) |
| 2021 | 0.9920 (0.4369) |
| 2022 | 1.1990 (0.3649) |
| 2023 | 0.8360 (0.0709) |
