Year | Value | 2015 | 11.557551692412 | 2014 | 10.963352233156 | 2013 | 10.438919724941 | 2012 | 10.330696612776 | 2011 | 10.254935323576 | 2010 | 11.519773035603 | 2009 | 12.170335760417 | 2008 | 13.167049866739 | 2007 | 16.151274105088 | 2006 | 19.713434264942 | 2005 | 23.658947919832 | 2004 | 24.089385983747 | 2003 | 22.873755409252 | 2002 | 23.085943623589 | 2001 | 22.891121892831 | 2000 | 22.622225912865 | 1999 | 24.467962464225 | 1998 | 28.025316701044 | 1997 | 29.750836774241 | 1996 | 30.73641907258 | 1995 | 29.289125667866 | 1994 | 29.9821142206 | 1993 | 30.045610217645 | 1992 | 29.763854588561 | 1991 | 27.838617908301 | 1990 | 28.639913794964 | 1989 | 30.161399872283 | 1988 | 30.317657140796 | 1987 | 31.873419241692 | 1986 | 31.010731967899 | 1985 | 29.26640695506 | 1984 | 30.653190835903 | 1983 | 28.457639728718 | 1982 | 29.806833522475 | 1981 | 33.821473414787 | 1980 | 39.597999215667 | 1979 | 42.550675641218 | 1978 | 44.445245210743 | 1977 | 45.553229994745 | 1976 | 45.076191641561 | 1975 | 47.66496910928 | 1974 | 51.939121498966 | 1973 | 51.613805778361 | 1972 | 50.178658093684 | 1971 | 53.128515084318 | 1970 | 54.34614762246 | 1969 | 57.043977378239 | 1968 | 65.516286270056 | 1967 | 66.240658022377 | 1966 | 68.761221078066 | 1965 | 69.591100629738 | 1964 | 68.167416614928 | 1963 | 69.710019248836 | 1962 | 69.217356666274 | 1961 | 69.75669076459 | 1960 | 72.127727974814 |
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