| Year | Value (SE) |
|---|---|
| 2007 | 0.5224 (0.0725) |
| 2009 | 0.4609 (0.0501) |
| 2010 | 0.6303 (0.0899) |
| 2011 | 0.5537 (0.0420) |
| 2012 | 0.4116 (0.0258) |
| 2013 | 0.4696 (0.0478) |
| 2014 | 0.4051 (0.0322) |
| 2015 | 0.3879 (0.1449) |
| 2016 | 0.4986 (0.0395) |
| 2018 | 0.4351 (0.0736) |
| 2019 | 0.3399 (0.0542) |
| 2020 | 0.5297 (0.1999) |
| 2021 | 0.6814 (0.7293) |
| 2022 | 2.3835 (2.8360) |
| 2023 | 0.4669 (0.1496) |
