| Year | Value (SE) |
|---|---|
| 2009 | 0.7315 (0.1680) |
| 2010 | 0.8781 (0.1251) |
| 2011 | 1.6742 (0.2212) |
| 2012 | 0.8308 (0.0851) |
| 2013 | 0.7712 (0.1110) |
| 2014 | 0.6783 (0.1173) |
| 2015 | 0.6756 (0.1032) |
| 2016 | 0.7064 (0.0520) |
| 2017 | 0.7990 (0.0600) |
| 2018 | 0.7581 (0.0693) |
| 2019 | 1.0089 (0.0985) |
| 2020 | 0.8420 (0.1876) |
| 2021 | 0.8273 (0.3186) |
| 2022 | 0.3451 (0.1356) |
| 2023 | 0.8164 (0.1812) |
| 2024 | 0.9421 (0.3677) |
