| Year | Value (SE) |
|---|---|
| 2000 | 0.7030 (0.0407) |
| 2001 | 0.7440 (0.0185) |
| 2002 | 0.7410 (0.0219) |
| 2010 | 0.8590 (0.0276) |
| 2011 | 0.7680 (0.0370) |
| 2012 | 0.8820 (0.0646) |
| 2013 | 0.6770 (0.0216) |
| 2014 | 0.7710 (0.0404) |
| 2015 | 0.7390 (0.0224) |
| 2016 | 0.7480 (0.0159) |
| 2017 | 0.8340 (0.0209) |
| 2018 | 0.7580 (0.0218) |
| 2019 | 0.6960 (0.0141) |
| 2020 | 0.7510 (0.0137) |
| 2021 | 0.7680 (0.0143) |
| 2022 | 0.7490 (0.0218) |
| 2023 | 0.6480 (0.0180) |
| 2024 | 0.7690 (0.0222) |
