| Year | Value | | 2020 | 1.0659535295427 | | 2019 | 1.0246753523905 | | 2018 | 1.0414093138142 | | 2017 | 1.0021530997742 | | 2016 | 1.0358369452417 | | 2015 | 1.0542396699358 | | 2014 | 1.0531032471897 | | 2013 | 1.0473286105891 | | 2012 | 1.0564153555908 | | 2011 | 0.95150888907202 | | 2010 | 0.992929931405 | | 2009 | 1.0051296578598 | | 2008 | 1.0655743862373 | | 2007 | 1.0886850182944 | | 2006 | 1.1137690974036 | | 2005 | 1.2325383310705 | | 2004 | 1.2178396686854 | | 2003 | 1.3567184059822 | | 2002 | 1.4558368898034 | | 2001 | 1.5323815991901 | | 2000 | 1.8535203107089 | | 1999 | 1.9236857907519 | | 1998 | 1.996703665918 | | 1997 | 2.0107022274285 | | 1996 | 2.0781183555208 | | 1995 | 2.1971313720403 | | 1994 | 1.608899287948 | | 1993 | 1.5825355273499 | | 1992 | 1.6762819382775 | | 1991 | 1.8414551810197 |
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