| Year | Value (SE) |
|---|---|
| 2008 | 0.8960 (0.0888) |
| 2009 | 1.0020 (0.0422) |
| 2010 | 1.1140 (0.2900) |
| 2011 | 0.9760 (0.0214) |
| 2012 | 0.8930 (0.0199) |
| 2013 | 0.9800 (0.0669) |
| 2014 | 0.9040 (0.0340) |
| 2015 | 0.7830 (0.1267) |
| 2016 | 0.8140 (0.0415) |
| 2017 | 0.8930 (0.0516) |
| 2018 | 1.0310 (0.1052) |
| 2019 | 0.7970 (0.0844) |
| 2020 | 1.6290 (0.5256) |
| 2021 | 1.0340 (1.2122) |
| 2022 | 1.4960 (0.3275) |
