| Year | Value (SE) |
|---|---|
| 2000 | 0.5197 (0.0949) |
| 2001 | 0.1431 (0.0109) |
| 2008 | 0.7421 (0.0372) |
| 2009 | 0.7579 (0.0261) |
| 2010 | 0.7309 (0.0369) |
| 2011 | 0.6322 (0.0181) |
| 2012 | 0.7726 (0.0313) |
| 2013 | 0.6995 (0.0607) |
| 2014 | 0.8083 (0.0622) |
| 2015 | 0.8963 (0.1713) |
| 2016 | 0.8054 (0.0396) |
| 2017 | 0.7707 (0.0362) |
| 2018 | 0.6899 (0.0545) |
| 2019 | 0.6140 (0.0341) |
| 2020 | 0.6791 (0.1408) |
| 2021 | 0.8831 (0.3758) |
| 2022 | 0.8175 (0.2752) |
| 2023 | 0.8102 (0.1279) |
