Year | Value | 2015 | 24.652083383955 | 2014 | 28.271185098968 | 2013 | 28.999817501676 | 2012 | 27.867140537354 | 2011 | 33.189384909052 | 2010 | 34.995935958764 | 2009 | 33.167426884333 | 2008 | 32.999445377104 | 2007 | 32.912545562192 | 2006 | 34.610933335352 | 2005 | 32.760965955636 | 2004 | 34.713023746303 | 2003 | 38.905709239167 | 2002 | 38.53408654236 | 2001 | 32.908493125918 | 2000 | 35.820806012441 | 1999 | 33.71615755024 | 1998 | 33.44056477808 | 1997 | 35.33219055825 | 1996 | 37.914321757229 | 1995 | 36.742891986462 | 1994 | 37.108811824214 | 1993 | 36.959997381858 | 1992 | 36.667672781666 | 1991 | 35.457449447284 | 1990 | 37.106640619339 | 1989 | 39.001045095084 | 1988 | 39.571824840354 | 1987 | 39.240311658111 | 1986 | 40.924730903514 | 1985 | 43.125455920272 | 1984 | 44.144679970954 | 1983 | 49.292552313666 | 1982 | 52.972199465207 | 1981 | 54.586585063095 | 1980 | 60.162057934108 | 1979 | 66.145247352198 | 1978 | 64.149924661337 | 1977 | 68.406469665439 | 1976 | 70.691104170736 | 1975 | 70.02815422842 | 1974 | 75.528474219761 | 1973 | 76.181324278211 | 1972 | 78.534555181871 | 1971 | 79.506651427592 | 1970 | 82.757077193894 | 1969 | 81.181016389275 | 1968 | 78.307017720653 | 1967 | 75.740023052213 | 1966 | 76.799648040512 | 1965 | 74.551321052298 | 1964 | 74.12238619804 | 1963 | 74.373987143962 | 1962 | 72.038244069247 | 1961 | 71.224149174305 | 1960 | 72.857935520486 |
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