| Year | Value | | 2014 | 75.04470837029 | | 2013 | 76.498183774034 | | 2012 | 78.915107997931 | | 2011 | 78.9987473425 | | 2010 | 78.44050318138 | | 2009 | 49.888463026206 | | 2008 | 57.69386027271 | | 2007 | 58.175861424791 | | 2006 | 58.345149439279 | | 2005 | 54.266883533038 | | 2004 | 43.438122399394 | | 2003 | 40.980344581804 | | 2002 | 42.107970839622 | | 2001 | 47.835703432931 | | 2000 | 52.521813005497 | | 1999 | 54.060761967596 | | 1998 | 50.638904004764 | | 1997 | 54.383605063002 | | 1996 | 52.238483181656 | | 1995 | 55.859528041947 | | 1994 | 66.792990539748 | | 1993 | 57.62869306761 | | 1992 | 60.311197507981 | | 1991 | 71.095633673865 | | 1990 | 69.275089894844 |
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