| Year | Value | | 2020 | 0.94856167032351 | | 2019 | 1.0116041948486 | | 2018 | 1.0172929817605 | | 2017 | 1.0031639632508 | | 2016 | 1.0187709791749 | | 2015 | 1.056541052219 | | 2014 | 1.0418519102258 | | 2013 | 0.9881637389363 | | 2012 | 1.2794774442338 | | 2011 | 1.3050383239753 | | 2010 | 1.3384502096126 | | 2009 | 1.3010983991337 | | 2008 | 1.2398337565386 | | 2007 | 1.1633178855859 | | 2005 | 1.1557432655172 | | 2004 | 1.1338256271578 | | 2003 | 1.4161620047172 | | 2002 | 1.4523532519343 | | 2001 | 1.434097798313 | | 2000 | 1.6390324731521 | | 1999 | 1.6662625852369 | | 1998 | 1.6171492561785 | | 1997 | 1.6344639040874 | | 1996 | 1.6881413908182 | | 1995 | 1.6989655652854 | | 1994 | 1.1917528390868 | | 1993 | 1.2814608479188 | | 1992 | 1.2930517163922 | | 1991 | 1.3721249295542 |
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