| Year | Value | | 2020 | 1.0358698149509 | | 2019 | 1.0312416007009 | | 2018 | 1.0696670855607 | | 2017 | 1.0362025855262 | | 2016 | 0.97105684514517 | | 2015 | 0.94204775325702 | | 2014 | 0.93894584816033 | | 2013 | 0.94436808022765 | | 2012 | 0.94532972630104 | | 2011 | 0.65044375636807 | | 2010 | 0.67238619559017 | | 2009 | 0.68038229190194 | | 2008 | 0.81353758398567 | | 2007 | 0.81806617337276 | | 2006 | 0.85191854070038 | | 2005 | 0.92072380485361 | | 2004 | 0.93560415627708 | | 2003 | 1.0632834111008 | | 2002 | 1.0580878768377 | | 2001 | 1.2905264210097 | | 2000 | 1.3667101346879 | | 1999 | 1.5216022572614 | | 1998 | 1.519536619883 | | 1997 | 1.5281159503146 | | 1996 | 1.5626161297486 | | 1995 | 1.7258234563752 | | 1994 | 1.4436433890587 | | 1993 | 1.4677932017125 | | 1992 | 1.5210714878248 | | 1991 | 1.7256643001303 |
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