Year % of total fuel combustion 1971 12.280701754385968 1972 14.285714285714285 1973 11.428571428571429 1974 13.432835820895523 1975 11.428571428571429 1976 10.256410256410255 1977 23.21428571428571 1978 30 1979 17.77777777777778 1980 8.888888888888888 1981 6.870229007633586 1982 4.580152671755725 1983 4.8 1984 4.285714285714286 1985 3.5211267605633805 1986 4.081632653061225 1987 4.3478260869565215 1988 4.891304347826086 1989 1.092896174863388 1990 1.5544041450777202 1991 1.5957446808510638 1992 1.7777777777777777 1993 1.1494252873563218 1994 0 1995 3.151862464183381 1996 0.5797101449275363 1997 0.5221932114882507 1998 0.49751243781094534 1999 0.49627791563275436 2000 0 2001 0 2002 0 2003 0 2004 0 2005 0 2006 0 2007 0 2008 0 2009 0 2010 0 2011 0 2012 0 2013 0 2014 0