| Year | Value (SE) |
|---|---|
| 2009 | 0.6617 (0.0801) |
| 2010 | 0.6407 (0.1451) |
| 2011 | 0.6199 (0.0575) |
| 2012 | 0.7505 (0.0954) |
| 2013 | 1.0603 (0.2317) |
| 2014 | 1.0040 (0.1698) |
| 2015 | 0.5075 (0.1522) |
| 2016 | 0.7439 (0.0748) |
| 2018 | 0.6332 (0.1108) |
| 2019 | 0.6704 (0.0741) |
| 2022 | 0.6602 (0.3894) |
| 2023 | 0.6636 (0.1646) |
| 2024 | 1.0122 (0.4644) |
