| Year | Value (SE) |
|---|---|
| 2006 | 0.9170 (0.2238) |
| 2008 | 0.7770 (0.1234) |
| 2009 | 0.8170 (0.1153) |
| 2010 | 0.7250 (0.0897) |
| 2011 | 0.7070 (0.0830) |
| 2012 | 0.8420 (0.0978) |
| 2015 | 0.5770 (0.3897) |
| 2016 | 0.3620 (0.2132) |
| 2019 | 0.6480 (0.2199) |
| 2020 | 0.8810 (0.3471) |
| 2021 | 1.1940 (0.8074) |
| 2022 | 0.5840 (0.1948) |
| 2023 | 0.2350 (0.1664) |
