| Year | Value | | 2020 | 1.4513705343791 | | 2019 | 1.3715633765147 | | 2018 | 1.3222575615333 | | 2017 | 1.3788999666412 | | 2016 | 1.1860718054864 | | 2015 | 1.2157226851096 | | 2014 | 0.67471375269042 | | 2013 | 0.68770745841662 | | 2012 | 0.71032396692258 | | 2011 | 0.74467094852462 | | 2010 | 0.74153308257156 | | 2009 | 0.74484797963089 | | 2008 | 0.76687606643703 | | 2007 | 0.80312952806101 | | 2006 | 0.81965029620113 | | 2005 | 0.82618567972361 | | 2003 | 0.85917909078465 | | 2002 | 0.88186848500973 | | 2001 | 0.91090499955613 | | 2000 | 0.94128157880042 | | 1999 | 0.97306185457343 | | 1998 | 1.0070020780085 | | 1997 | 1.0206420530474 | | 1996 | 1.0451986408875 | | 1995 | 1.0703559477775 | | 1994 | 1.042218371278 | | 1993 | 1.075022917534 | | 1992 | 1.1317058717016 | | 1991 | 1.3013208406533 |
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