Year % of output 1960 9.911190053285967 1961 9.39887080704085 1962 9.241573033707866 1963 10.595028872709014 1964 10.267355650415636 1965 10.054512416717142 1966 10.502612141956403 1967 10.964417968121074 1968 11.490772779700114 1969 10.691502934422047 1970 10.054505392554795 1971 10.05009712708312 1972 10.050698212220938 1973 10.325955734406438 1974 11.041032870816947 1975 10.465339563464124 1976 9.36388995241481 1977 10.104546559688792 1978 10.070882813219184 1979 11.375543912618772 1980 12.133190118152525 1981 11.87938232075548 1982 12.492467610726123 1983 12.513255567338282 1984 12.217031979877829 1985 11.52868289546743 1986 13.722131250787253 1987 12.44109755822605 1988 13.128538128538128 1989 12.003304895857351 1990 11.610447839007351 1991 12.55021080237692 1992 13.357191648599684 1993 13.890093214827662 1994 15.119827377076392 1995 15.964613261910559 1996 16.712698446163902 1997 17.989079925650557 1998 18.730521878546593 1999 18.503091721058055 2000 19.016666399833497 2001 19.009166836422896 2002 18.494590417310665 2003 17.108997659712195 2004 15.42356235650108 2005 14.84600755760824 2006 14.07268333910005 2007 13.910669353407323 2008 13.850053926559083 2009 14.881526805330267 2010 14.309117078898526 2011 14.110718286957319 2012 14.888348865951832 2013 15.462578179001806 2014 14.816064263403753