| Year | Value | | 2014 | 483.47260293753 | | 2013 | 456.56275999455 | | 2012 | 467.01166561328 | | 2011 | 462.53389197102 | | 2010 | 462.30077391498 | | 2009 | 452.83032322993 | | 2008 | 452.1740356432 | | 2007 | 468.31577791381 | | 2006 | 466.62849147921 | | 2005 | 457.32263941513 | | 2004 | 453.83433909245 | | 2003 | 377.29154186268 | | 2002 | 266.75658758255 | | 2001 | 277.37658607927 | | 2000 | 125.22156478556 | | 1999 | 68.866499522174 | | 1998 | 48.749659860328 | | 1997 | 54.050049498466 | | 1996 | 45.523653549324 | | 1995 | 45.848528005756 | | 1994 | 44.391178011105 | | 1993 | 51.245036165058 | | 1992 | 54.064300039929 | | 1991 | 54.788762773137 | | 1990 | 41.192294425081 | | 1989 | 38.815355354578 | | 1988 | 34.036255326558 | | 1987 | 41.728394737965 | | 1986 | 36.793762132743 | | 1985 | 31.703307514591 | | 1984 | 30.01716611717 | | 1983 | 38.722954770273 | | 1982 | 49.656241852616 | | 1981 | 37.542906946426 | | 1980 | 37.849626064094 | | 1979 | 37.743160310299 | | 1978 | 62.563261512199 | | 1977 | 59.535440231773 | | 1976 | 64.575949600817 | | 1975 | 58.740286726797 | | 1974 | 72.095285723294 | | 1973 | 61.269217599764 | | 1972 | 54.059636017261 | | 1971 | 55.201910264424 |
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