| Year | Value | | 2014 | 1,597.1422221985 | | 2013 | 1,535.0912385888 | | 2012 | 1,484.4158270429 | | 2011 | 1,415.0214207021 | | 2010 | 1,383.320265289 | | 2009 | 1,315.9120780849 | | 2008 | 1,368.4837930439 | | 2007 | 1,349.8959712221 | | 2006 | 1,320.850721357 | | 2005 | 1,225.5629384181 | | 2004 | 1,119.9665779326 | | 2003 | 1,354.6188882955 | | 2002 | 1,379.2905846107 | | 2001 | 1,277.765473455 | | 2000 | 1,316.9740367139 | | 1999 | 1,270.422644386 | | 1998 | 1,092.2316323128 | | 1997 | 638.03086008032 | | 1996 | 634.772925774 | | 1995 | 498.49086750245 | | 1994 | 528.35769958676 | | 1993 | 510.81866412604 | | 1992 | 543.26313323478 | | 1991 | 400.91217825012 | | 1990 | 391.4992893818 | | 1989 | 336.38809444024 | | 1988 | 382.92665118279 | | 1987 | 481.41861604848 | | 1986 | 488.0746682534 | | 1985 | 480.22701867525 | | 1984 | 448.09828044872 | | 1983 | 369.27303478828 | | 1982 | 331.00697442169 | | 1981 | 446.88036723711 | | 1980 | 444.94249278988 | | 1979 | 475.48252144026 | | 1978 | 412.88755064878 | | 1977 | 424.97083917202 | | 1976 | 384.50386394867 | | 1975 | 405.76110266755 | | 1974 | 367.3736819038 | | 1973 | 402.99448608721 | | 1972 | 310.70091629256 | | 1971 | 329.79400809724 |
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