Year | Value | 2014 | 68.052331641509 | 2013 | 62.934952884175 | 2012 | 56.166523100587 | 2011 | 51.591231163578 | 2010 | 47.435060332231 | 2009 | 41.415201107802 | 2008 | 40.292990139953 | 2007 | 38.92864039955 | 2006 | 36.917571044678 | 2005 | 33.045075289848 | 2004 | 30.344872060575 | 2003 | 28.236064101496 | 2002 | 25.888796503718 | 2001 | 26.239177389763 | 2000 | 22.481844344273 | 1999 | 22.742087562907 | 1998 | 23.567986267467 | 1997 | 23.728848989148 | 1996 | 24.314358265481 | 1995 | 23.905407243053 | 1994 | 23.480673239445 | 1993 | 23.144846659535 | 1992 | 21.47599742934 | 1991 | 21.787264582899 | 1990 | 22.599071604239 | 1989 | 18.746230459923 | 1988 | 19.410697950062 | 1987 | 20.559154392879 | 1986 | 20.142172863794 | 1985 | 20.081435308798 | 1984 | 21.478008381525 | 1983 | 20.400057151545 | 1982 | 19.56284932148 | 1981 | 19.040257133926 | 1980 | 18.171168342311 | 1979 | 17.146725595398 | 1978 | 15.616304764885 | 1977 | 14.987378846333 | 1976 | 16.060629450851 | 1975 | 16.64972600969 | 1974 | 17.212571414308 | 1973 | 17.951206340614 | 1972 | 18.868348706354 | 1971 | 18.96933682305 |
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