| Year | Value (SE) |
|---|---|
| 2001 | 0.4525 (0.0559) |
| 2006 | 0.8519 (0.0254) |
| 2007 | 0.8279 (0.0573) |
| 2008 | 0.7374 (0.0349) |
| 2009 | 0.9142 (0.0501) |
| 2010 | 0.8470 (0.0228) |
| 2011 | 0.8921 (0.0287) |
| 2012 | 0.8620 (0.0296) |
| 2013 | 0.8309 (0.0967) |
| 2014 | 0.9426 (0.1087) |
| 2015 | 0.7440 (0.2300) |
| 2016 | 0.6390 (0.0693) |
| 2018 | 0.6595 (0.0690) |
| 2020 | 1.1617 (0.3115) |
| 2021 | 0.7422 (0.2609) |
| 2022 | 0.6393 (0.1203) |
| 2023 | 0.7450 (0.1601) |
| 2024 | 0.6389 (0.2394) |
