| Year | Value (SE) |
|---|---|
| 2000 | 1.0100 (0.0815) |
| 2001 | 0.8950 (0.0084) |
| 2002 | 0.9490 (0.0196) |
| 2003 | 0.9090 (0.0526) |
| 2004 | 0.9080 (0.0441) |
| 2005 | 0.8690 (0.0223) |
| 2006 | 0.9240 (0.0243) |
| 2007 | 0.9720 (0.0383) |
| 2008 | 0.8840 (0.0342) |
| 2009 | 1.0880 (0.0579) |
| 2010 | 1.0210 (0.1192) |
| 2011 | 1.0630 (0.0405) |
| 2012 | 0.9350 (0.0283) |
| 2013 | 1.0310 (0.0992) |
| 2014 | 0.8890 (0.0583) |
| 2015 | 1.0640 (0.1732) |
| 2016 | 0.8500 (0.0341) |
| 2019 | 1.0360 (0.1079) |
| 2020 | 1.1490 (0.3276) |
| 2021 | 1.3410 (0.9925) |
| 2022 | 1.2320 (0.3873) |
| 2023 | 0.9070 (0.1006) |
