| Year | Value | | 2014 | -103.09132954766 | | 2013 | -112.28375075832 | | 2012 | -107.21107341771 | | 2011 | -106.70815553138 | | 2010 | -79.04613071007 | | 2009 | -74.399756646194 | | 2008 | -73.633864363919 | | 2007 | -74.094632457242 | | 2006 | -70.831749545446 | | 2005 | -55.914624816494 | | 2004 | -50.17429110757 | | 2003 | -53.988290910106 | | 2002 | -50.286293134744 | | 2001 | -51.818404501199 | | 2000 | -52.5666611423 | | 1999 | -65.673158990399 | | 1998 | -67.125648144533 | | 1997 | -62.428028038793 | | 1996 | -64.250447695697 | | 1995 | -63.951497646629 | | 1994 | -74.906761118456 | | 1993 | -63.970972331732 | | 1992 | -73.712490214845 | | 1991 | -76.991525770148 | | 1990 | -70.860720121647 | | 1989 | -83.16076969578 | | 1988 | -81.172717876589 | | 1987 | -82.511160781707 | | 1986 | -87.739885261393 | | 1985 | -94.402988662808 | | 1984 | -110.66801609658 | | 1983 | -91.370613876112 | | 1982 | -90.031834287265 | | 1981 | -117.27024184595 | | 1980 | -124.47382577627 | | 1979 | -126.8499032093 | | 1978 | -134.23199639403 | | 1977 | -147.24971948922 | | 1976 | -145.74052971001 | | 1975 | -129.27436230804 | | 1974 | -145.27155850681 | | 1973 | -148.68872405116 | | 1972 | -123.88108398245 | | 1971 | -104.65402437209 |
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