| Year | Value (SE) |
|---|---|
| 2000 | 0.7430 (0.0589) |
| 2001 | 0.7470 (0.0274) |
| 2008 | 0.9960 (0.0397) |
| 2009 | 0.9160 (0.0180) |
| 2010 | 0.9320 (0.0387) |
| 2011 | 0.9140 (0.0133) |
| 2012 | 0.9550 (0.0193) |
| 2013 | 1.2440 (0.0911) |
| 2014 | 1.0580 (0.0600) |
| 2015 | 0.8910 (0.1517) |
| 2016 | 1.0400 (0.0368) |
| 2017 | 0.9400 (0.0210) |
| 2018 | 0.9230 (0.0281) |
| 2019 | 0.9300 (0.0213) |
| 2020 | 1.1780 (0.2088) |
| 2021 | 1.2060 (0.4995) |
| 2022 | 1.2700 (0.3386) |
| 2023 | 1.0500 (0.1183) |
