Year % of output 1971 11.837443980366452 1972 11.936862505671284 1973 11.9887794296381 1974 11.752630833844556 1975 12.023629485411188 1976 12.065736454220414 1977 12.161173776733964 1978 11.943678083574456 1979 12.056613453239581 1980 12.494750221043324 1981 11.65747105042743 1982 12.8648507767528 1983 12.484817490251231 1984 11.787269836656142 1985 12.56935592517747 1986 13.31661160495691 1987 14.018518484557843 1988 13.96352208749514 1989 14.828675206800497 1990 14.53446138671927 1991 15.049653581493715 1992 14.870236611180367 1993 15.442828168276884 1994 15.826783044799152 1995 16.101192152199452 1996 16.164017993998673 1997 16.205136785744166 1998 15.814550057583766 1999 15.920661949977742 2000 15.864335068584044 2001 15.721860589867646 2002 15.73322814212027 2003 14.94215377612563 2004 16.01134867674429 2005 16.07676847756544 2006 16.144348841918873 2007 15.999170483961755 2008 15.869261825442512 2009 16.229663778567456 2010 15.258946660132965 2011 14.816084584262287 2012 14.780575793302901 2013 14.750888498891882 2014 15.618667277425265