| Year | Value (SE) |
|---|---|
| 2000 | 0.4116 (0.0752) |
| 2001 | 0.1087 (0.0083) |
| 2008 | 0.6152 (0.0308) |
| 2009 | 0.6306 (0.0218) |
| 2010 | 0.5921 (0.0296) |
| 2011 | 0.5039 (0.0146) |
| 2012 | 0.5786 (0.0236) |
| 2013 | 0.5722 (0.0496) |
| 2014 | 0.6871 (0.0529) |
| 2015 | 0.7556 (0.1444) |
| 2016 | 0.6395 (0.0315) |
| 2017 | 0.5672 (0.0267) |
| 2018 | 0.5244 (0.0414) |
| 2019 | 0.4912 (0.0273) |
| 2020 | 0.5318 (0.1103) |
| 2021 | 0.7409 (0.3153) |
| 2022 | 0.6172 (0.2078) |
| 2023 | 0.6846 (0.1080) |
