| Year | Value | | 2017 | 69.48246178 | | 2016 | 68.50087368 | | 2015 | 67.60044348 | | 2014 | 66.7 | | 2013 | 65.8 | | 2012 | 64.8960101 | | 2011 | 64 | | 2010 | 63 | | 2009 | 62.83 | | 2008 | 62.82 | | 2007 | 61.07 | | 2006 | 59.36168727 | | 2005 | 57.7034045 | | 2004 | 56.09901476 | | 2003 | 54.53425983 | | 2002 | 44.15478903 | | 2001 | 35.46413689 | | 2000 | 31.74781123 | | 1999 | 21.60261331 | | 1998 | 14.65444717 | | 1997 | 7.954504682 | | 1996 | 1.796719191 | | 1995 | 0.053940342 | | 1994 | 0.064712121 |
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