| Year | Value | | 2014 | 3,548.868092048 | | 2013 | 3,516.8059449788 | | 2012 | 3,960.0330636822 | | 2011 | 4,164.7526910643 | | 2010 | 4,516.2992194291 | | 2009 | 4,523.9582564489 | | 2008 | 4,509.3785186609 | | 2007 | 4,335.7082262055 | | 2006 | 4,198.2570269405 | | 2005 | 4,062.4379256014 | | 2004 | 3,914.8548519462 | | 2003 | 3,891.6379267256 | | 2002 | 3,683.5900036042 | | 2001 | 3,438.9477939119 | | 2000 | 3,355.7011590984 | | 1999 | 3,159.0811507085 | | 1998 | 3,077.6463385302 | | 1997 | 2,846.8886459841 | | 1996 | 2,795.2703117294 | | 1995 | 2,762.0017207433 | | 1994 | 3,031.5805429371 | | 1993 | 2,978.2587114067 | | 1992 | 2,803.4465611508 | | 1991 | 2,431.6040953069 | | 1990 | 2,362.7140139505 | | 1989 | 2,217.1009989815 | | 1988 | 2,009.3631101809 | | 1987 | 1,868.8221917006 | | 1986 | 1,794.3468658114 | | 1985 | 1,698.8672396072 | | 1984 | 1,632.674612813 | | 1983 | 1,624.0810655329 | | 1982 | 1,526.8008853434 | | 1981 | 1,440.6915319353 | | 1980 | 1,427.883773205 | | 1979 | 1,375.7964059552 | | 1978 | 1,302.7598930683 | | 1977 | 1,233.977337473 | | 1976 | 1,154.3179814693 | | 1975 | 1,037.2382485093 | | 1974 | 1,033.018031561 | | 1973 | 1,189.479103434 | | 1972 | 1,099.4101479262 | | 1971 | 954.35691086306 |
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