Year % of output 1971 4.25531914893617 1972 4.25531914893617 1973 4.081632653061225 1974 4.166666666666666 1975 2 1976 3.8461538461538463 1977 3.9215686274509802 1978 3.9215686274509802 1979 3.7037037037037033 1980 3.7037037037037033 1981 3.571428571428571 1982 3.389830508474576 1983 3.278688524590164 1984 3.278688524590164 1985 3.1746031746031744 1986 3.076923076923077 1987 11.428571428571429 1988 10.81081081081081 1989 4.938271604938271 1990 6.329113924050633 1991 5.434782608695652 1992 3.0303030303030303 1993 2.912621359223301 1994 2.8301886792452833 1995 2.7777777777777777 1996 2.727272727272727 1997 2.7027027027027026 1998 3.4482758620689653 1999 3.3333333333333335 2000 3.2 2001 3.1746031746031744 2002 3.10077519379845 2003 2.9850746268656714 2004 2.941176470588235 2005 2.7586206896551726 2006 3.3112582781456954 2007 3.225806451612903 2008 3.0120481927710845 2009 2.8735632183908044 2010 2.824858757062147 2011 2.923976608187134 2012 2.840909090909091 2013 3.1746031746031744 2014 3.0303030303030303