| Year | Value | | 2022 | 1.3580638321418 | | 2021 | 1.3974119036846 | | 2020 | 1.3224499490378 | | 2019 | 1.1522925502176 | | 2018 | 1.0884494805814 | | 2017 | 0.95665542172635 | | 2016 | 0.99612810262019 | | 2015 | 0.94658209556062 | | 2014 | 0.96622781806476 | | 2013 | 1.0150837197256 | | 2012 | 1.0632168166006 | | 2011 | 1.0778364989687 | | 2010 | 1.1947721814134 | | 2009 | 1.3105641425074 | | 2008 | 1.2324715671579 | | 2007 | 1.4237162889914 | | 2006 | 1.5678353362801 | | 2005 | 1.7788222002611 | | 2004 | 1.7137031730213 | | 2003 | 1.8927640441762 | | 2002 | 1.8244069682627 | | 2001 | 1.7512495575883 | | 2000 | 1.8773569561649 | | 1999 | 1.8590699232123 | | 1998 | 1.8259318203536 | | 1997 | 1.6620457907056 | | 1996 | 1.7319046875665 | | 1995 | 1.8436227729977 | | 1994 | 2.2834008576376 | | 1993 | 2.3304040663427 |
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