Data Table
| Year | Value (SE) |
| 2000 | 1.3048 (0.2879) |
| 2001 | 0.6140 (0.0635) |
| 2002 | 0.8225 (0.1376) |
| 2003 | 0.9411 (0.0667) |
| 2004 | 0.6803 (0.1455) |
| 2005 | 0.7916 (0.0635) |
| 2006 | 0.7680 (0.0602) |
| 2007 | 0.8814 (0.0302) |
| 2008 | 0.8945 (0.0734) |
| 2009 | 0.6440 (0.0556) |
| 2010 | 0.7779 (0.0822) |
| 2011 | 0.8366 (0.0816) |
| 2012 | 0.9478 (0.0428) |
| 2013 | 0.8772 (0.0722) |
| 2014 | 0.8586 (0.0634) |
| 2015 | 0.7424 (0.0923) |
| 2016 | 0.7503 (0.0557) |
| 2017 | 0.8441 (0.0619) |
| 2018 | 0.6915 (0.0680) |
| 2019 | 0.7012 (0.0610) |
| 2020 | 0.9341 (0.1151) |
| 2021 | 0.8448 (0.3124) |
| 2022 | 0.8774 (0.1920) |
| 2023 | 0.7066 (0.0822) |
| 2024 | 0.6855 (0.3341) |