| Year | Value | | 2014 | 1,447.6669926454 | | 2013 | 1,430.6308333846 | | 2012 | 1,372.8536451006 | | 2011 | 1,325.1955311713 | | 2010 | 1,295.7005928125 | | 2009 | 1,328.0824518963 | | 2008 | 1,318.7475064534 | | 2007 | 1,300.2792308388 | | 2006 | 1,227.2847966766 | | 2005 | 1,156.6662048775 | | 2004 | 1,177.9646929515 | | 2003 | 1,196.6015124093 | | 2002 | 1,188.2667321752 | | 2001 | 1,160.5038707252 | | 2000 | 1,140.0358605704 | | 1999 | 1,081.923965596 | | 1998 | 1,045.8811947842 | | 1997 | 1,039.4495281879 | | 1996 | 972.35883032712 | | 1995 | 916.10433632176 | | 1994 | 894.44427758194 | | 1993 | 836.18256508157 | | 1992 | 900.52178519008 | | 1991 | 1,044.9128657475 | | 1990 | 1,208.938257292 | | 1989 | 1,182.6521177975 | | 1988 | 1,144.3169794482 | | 1987 | 1,087.0628290553 | | 1986 | 1,068.1472681301 | | 1985 | 997.72944131487 | | 1984 | 1,112.6080779181 | | 1983 | 1,050.9193616444 | | 1982 | 1,010.0037602658 | | 1981 | 967.95876757617 | | 1980 | 843.50186005719 | | 1979 | 863.86185739916 | | 1978 | 787.05149216042 | | 1977 | 718.73527404264 | | 1976 | 667.23175481535 | | 1975 | 618.22697506544 | | 1974 | 565.80692555751 | | 1973 | 540.22811973942 | | 1972 | 506.90953246211 | | 1971 | 497.02466587389 |
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