| Year | Value | | 2014 | -97.890193235318 | | 2013 | -94.449700920734 | | 2012 | -101.01940793073 | | 2011 | -107.95942485671 | | 2010 | -113.16007526255 | | 2009 | -115.93701254213 | | 2008 | -123.56624212927 | | 2007 | -123.51644935123 | | 2006 | -119.7798249301 | | 2005 | -114.8764794396 | | 2004 | -114.92357585086 | | 2003 | -101.47645550038 | | 2002 | -110.62359694493 | | 2001 | -125.82943723171 | | 2000 | -131.87469589444 | | 1999 | -129.85230167245 | | 1998 | -118.82447830274 | | 1997 | -93.058113067657 | | 1996 | -75.748449246796 | | 1995 | -70.179301942478 | | 1994 | -69.315635829633 | | 1993 | -68.144797719994 | | 1992 | -71.570575110202 | | 1991 | -72.865372452759 | | 1990 | -124.01341869924 | | 1989 | -148.48099054526 | | 1988 | -143.53247879126 | | 1987 | -122.8285028741 | | 1986 | -112.07414860418 | | 1985 | -105.23940322364 | | 1984 | -97.094602321556 | | 1983 | -79.901854404089 | | 1982 | -85.222634215992 | | 1981 | -89.35280891135 | | 1980 | -192.68417133551 | | 1979 | -242.63482753019 | | 1978 | -192.3979052384 | | 1977 | -200.84695093972 | | 1976 | -213.21728904054 | | 1975 | -201.2188107269 | | 1974 | -219.03862283288 | | 1973 | -216.80464787988 | | 1972 | -177.76684433301 | | 1971 | -178.67300432259 |
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