| Year | Value | | 2015 | 64.967363325536 | | 2014 | -126.96788342898 | | 2013 | -138.21773379899 | | 2012 | -140.14453488044 | | 2011 | -149.07486150208 | | 2010 | -144.13707705761 | | 2009 | -144.99682124692 | | 2008 | -166.55911219868 | | 2007 | -176.55149464885 | | 2006 | -188.67586441956 | | 2005 | -200.26356776396 | | 2004 | -205.26134633712 | | 2003 | -206.5266007728 | | 2002 | -190.78466534096 | | 2001 | -211.73488042125 | | 2000 | -238.3074858312 | | 1999 | -225.77691757507 | | 1998 | -241.68616789521 | | 1997 | -230.81841902642 | | 1996 | -233.9899826927 | | 1995 | -237.53977669376 | | 1994 | -241.51307879553 | | 1993 | -261.13787799171 | | 1992 | -269.08131401513 | | 1991 | -274.55089148554 | | 1990 | -289.89417307388 | | 1989 | -263.44833855711 | | 1988 | -262.94150529864 | | 1987 | -242.0200137055 | | 1986 | -253.141669902 | | 1985 | -227.16499903842 | | 1984 | -268.93648272373 | | 1983 | -287.33022087213 | | 1982 | -322.68320183462 | | 1981 | -458.15232494897 | | 1980 | -633.50644308892 | | 1979 | -814.38311598026 | | 1978 | -952.0773641869 | | 1977 | -1,087.9013189319 | | 1976 | -1,191.2434736976 | | 1975 | -1,164.869264555 | | 1974 | -1,410.0024297789 | | 1973 | -1,524.1816480433 | | 1972 | -1,572.5370846753 | | 1971 | -1,471.6745848983 |
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