Year % of output 1960 18.244332223057913 1961 17.78906025481368 1962 15.834970530451868 1963 16.584932617677723 1964 14.929214929214929 1965 15.108435254066322 1966 14.59699036598636 1967 13.515044073472202 1968 12.811333522516428 1969 12.554769774771312 1970 12.610340479192939 1971 12.1571811317691 1972 11.954649193845247 1973 11.496167063177372 1974 10.141615465307957 1975 10.240200735706107 1976 9.537789231889741 1977 9.806988963091628 1978 9.729570242552498 1979 9.774314012014937 1980 9.124201197517074 1981 8.109385795847121 1982 9.310521029725301 1983 9.11178907590702 1984 9.37378287301238 1985 9.423883710007404 1986 9.33883395202296 1987 9.173038927348687 1988 9.74066270276511 1989 8.421195652173912 1990 9.282700421940929 1991 9.395214185552089 1992 9.472878111040204 1993 9.552300259265694 1994 9.418776646654486 1995 9.637310079953622 1996 8.996625616473914 1997 7.453462122053218 1998 9.539174319516837 1999 9.462827382832046 2000 8.72076443615591 2001 7.714948920267563 2002 8.022357732049 2003 8.754707302001842 2004 8.700461229269987 2005 8.96888873533832 2006 8.50017930726499 2007 8.441917711097638 2008 8.299622481333085 2009 8.375332769153285 2010 9.184768034325556 2011 8.927634264388594 2012 8.734716372617727 2013 9.484623994030805 2014 9.599234767175004