Year | Value | 2015 | 44.721697726193 | 2014 | 17.363318884523 | 2013 | 17.158938266756 | 2012 | 17.525542220557 | 2011 | 15.932796883538 | 2010 | 16.242936581541 | 2009 | 15.933117277439 | 2008 | 16.399576190312 | 2007 | 16.859179340637 | 2006 | 16.722095960469 | 2005 | 16.997222360111 | 2004 | 18.506628999189 | 2003 | 18.489701334035 | 2002 | 18.250715986033 | 2001 | 17.348946272048 | 2000 | 18.829366880031 | 1999 | 19.605833295788 | 1998 | 17.702909566533 | 1997 | 19.449322467306 | 1996 | 18.863328500695 | 1995 | 18.397253871149 | 1994 | 19.296167139046 | 1993 | 19.186027888158 | 1992 | 17.556787216066 | 1991 | 16.112361838924 | 1990 | 18.20194419521 | 1989 | 15.595820954004 | 1988 | 16.788011938311 | 1987 | 13.590016220903 | 1986 | 13.120725795798 | 1985 | 13.389991363392 | 1984 | 15.006104840319 | 1983 | 16.973350539229 | 1982 | 19.119949236594 | 1981 | 19.548866705703 | 1980 | 20.962540587978 | 1979 | 21.377932201516 | 1978 | 21.183855519964 | 1977 | 21.858248705766 | 1976 | 23.081388614628 | 1975 | 23.158105263332 | 1974 | 26.369913346297 | 1973 | 26.964131780926 | 1972 | 25.995143109638 | 1971 | 26.608337108322 | 1970 | 71.252639138014 | 1969 | 69.854783901421 | 1968 | 66.350891541831 | 1967 | 64.445464417124 | 1966 | 58.011149012344 | 1965 | 55.70481822776 | 1964 | 53.944612037255 | 1963 | 51.156835470169 | 1962 | 45.336293738735 | 1961 | 41.616145819788 | 1960 | 39.249156593013 |
|