Year % of output 1971 10.15916017609211 1972 9.831660475776497 1973 9.752072315367014 1974 9.8175313059034 1975 11.05544763657431 1976 10.699629335451416 1977 11.263999012741802 1978 11.721600765687622 1979 11.274939560585532 1980 12.680703168286907 1981 12.662529931254667 1982 12.85664142807 1983 14.303653233495336 1984 13.963883823333184 1985 13.948967193195625 1986 16.684692773911802 1987 15.75549107400219 1988 14.024040117903763 1989 17.083407574587714 1990 18.312968072526605 1991 18.934039497976617 1992 20.395125355666504 1993 20.26601273223334 1994 17.920535755809446 1995 17.70200701335522 1996 17.52432339350802 1997 16.263243796508895 1998 15.16375722855753 1999 14.828438987410989 2000 14.832977167922618 2001 14.256228152915718 2002 17.170497199625828 2003 15.265674236661958 2004 15.41955772974592 2005 15.125460939795813 2006 15.1175738520993 2007 16.717404459339942 2008 13.38278346107036 2009 14.747496288519427 2010 13.425353057167719 2011 14.434796032573038 2012 13.599799449962028 2013 16.018349415435942 2014 14.657381534942306