| Year | Value | | 2014 | 101.93930274147 | | 2013 | 98.672904256036 | | 2012 | 96.304080825784 | | 2011 | 85.940135639775 | | 2010 | 94.988914671735 | | 2009 | 70.976949712353 | | 2008 | 84.299637954748 | | 2007 | 79.752621606747 | | 2006 | 63.729517431712 | | 2005 | 77.612535958552 | | 2004 | 77.761513233312 | | 2003 | 66.32038994675 | | 2002 | 66.375945709373 | | 2001 | 61.076731095418 | | 2000 | 57.451746916118 | | 1999 | 55.045150755056 | | 1998 | 59.522171211878 | | 1997 | 54.772806739201 | | 1996 | 59.921518225021 | | 1995 | 55.955367381182 | | 1994 | 48.313548034461 | | 1993 | 47.736105535362 | | 1992 | 52.246636174113 | | 1991 | 53.103454379707 | | 1990 | 49.72141507071 | | 1989 | 45.096759780179 | | 1988 | 42.706235798718 | | 1987 | 39.254064880828 | | 1986 | 38.972280804501 | | 1985 | 34.869874887155 | | 1984 | 33.261387472929 | | 1983 | 32.686658652137 | | 1982 | 34.48793610044 | | 1981 | 36.398499215472 | | 1980 | 35.444713786268 | | 1979 | 35.51061157616 | | 1978 | 33.241141249684 | | 1977 | 34.031091010997 | | 1976 | 34.147085094952 | | 1975 | 33.674332635673 | | 1974 | 33.373074730929 | | 1973 | 33.259488012831 | | 1972 | 31.790186958501 | | 1971 | 30.087527740488 |
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