| Year | Value (SE) |
|---|---|
| 2000 | 0.4825 (0.0396) |
| 2001 | 0.4298 (0.0168) |
| 2008 | 0.7827 (0.0320) |
| 2009 | 0.7728 (0.0151) |
| 2010 | 0.7074 (0.0318) |
| 2011 | 0.7008 (0.0111) |
| 2012 | 0.6988 (0.0153) |
| 2013 | 0.9199 (0.0706) |
| 2014 | 0.9425 (0.0545) |
| 2015 | 0.6753 (0.1179) |
| 2016 | 0.7300 (0.0266) |
| 2017 | 0.6697 (0.0161) |
| 2018 | 0.7134 (0.0229) |
| 2019 | 0.7150 (0.0168) |
| 2020 | 0.8467 (0.1498) |
| 2021 | 1.3619 (0.5640) |
| 2022 | 0.8208 (0.2178) |
| 2023 | 0.7338 (0.0820) |
