| Year | Value (SE) |
|---|---|
| 2007 | 0.5087 (0.0664) |
| 2009 | 0.6474 (0.0623) |
| 2010 | 0.6799 (0.0942) |
| 2011 | 0.6703 (0.0341) |
| 2012 | 0.4412 (0.0191) |
| 2013 | 0.5706 (0.0500) |
| 2014 | 0.5409 (0.0335) |
| 2015 | 0.7590 (0.2688) |
| 2016 | 0.5254 (0.0288) |
| 2018 | 0.5030 (0.0672) |
| 2019 | 0.4733 (0.0521) |
| 2020 | 0.4141 (0.1456) |
| 2021 | 0.8350 (0.8719) |
| 2022 | 0.7581 (0.4968) |
| 2023 | 0.8091 (0.1981) |
