| Year | Value (SE) |
|---|---|
| 2003 | 0.5140 (0.0202) |
| 2010 | 0.6250 (0.1090) |
| 2011 | 0.5180 (0.0937) |
| 2012 | 0.4180 (0.0539) |
| 2013 | 0.4870 (0.1052) |
| 2014 | 0.3970 (0.0881) |
| 2015 | 0.2780 (0.0766) |
| 2017 | 0.4890 (0.0687) |
| 2018 | 0.5110 (0.1317) |
| 2019 | 0.4880 (0.1074) |
| 2020 | 0.5650 (0.1460) |
| 2021 | 1.0300 (0.9954) |
| 2022 | 0.7230 (0.4029) |
| 2023 | 0.3040 (0.0581) |
