| Year | Value (SE) |
|---|---|
| 2005 | 0.8037 (0.5250) |
| 2006 | 0.8126 (0.0911) |
| 2007 | 0.3784 (0.2389) |
| 2008 | 0.7372 (0.1508) |
| 2009 | 0.7952 (0.0564) |
| 2010 | 0.9501 (0.1546) |
| 2011 | 0.9032 (0.0584) |
| 2012 | 0.8326 (0.0614) |
| 2013 | 0.7774 (0.0812) |
| 2014 | 0.6510 (0.0791) |
| 2016 | 0.7711 (0.0459) |
| 2017 | 0.7012 (0.0558) |
| 2018 | 0.8929 (0.1172) |
| 2019 | 0.8127 (0.0814) |
| 2020 | 0.7192 (0.2296) |
| 2021 | 0.7303 (0.2644) |
| 2022 | 0.7178 (0.2461) |
| 2023 | 0.6036 (0.1369) |
| 2024 | 1.1191 (0.6282) |
