| Year | Value | | 2020 | 1.1303894266106 | | 2019 | 1.1385071518892 | | 2018 | 1.1316231050444 | | 2017 | 1.1459330935252 | | 2016 | 1.1425131231915 | | 2015 | 1.1364261391763 | | 2014 | 1.1342844199614 | | 2013 | 1.1381942765504 | | 2012 | 1.107765195886 | | 2011 | 1.1684412668489 | | 2010 | 1.0700986543425 | | 2009 | 1.0656464203668 | | 2008 | 1.0729430795541 | | 2007 | 1.0814440955586 | | 2006 | 1.1052233698534 | | 2005 | 1.1117734804579 | | 2004 | 1.1262727554137 | | 2003 | 1.1713306299505 | | 2002 | 1.1646356791672 | | 2001 | 1.1562692212132 | | 2000 | 1.2033722152159 | | 1999 | 1.1103483315868 | | 1998 | 1.1163716464581 | | 1997 | 1.001862006619 | | 1996 | 1.1954424084759 | | 1995 | 1.3068521068569 | | 1994 | 0.92252618717827 | | 1993 | 0.95707173165032 | | 1992 | 0.93766732226069 | | 1991 | 0.95921876343076 |
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