Year % of total fuel combustion 1971 30.19891500904159 1972 32.07236842105263 1973 27.1712158808933 1974 29.82456140350877 1975 17.181208053691275 1976 21.290322580645164 1977 19.444444444444446 1978 18 1979 18.857142857142858 1980 19.571865443425075 1981 19.785276073619634 1982 25.31418312387792 1983 26.763110307414102 1984 26.053639846743298 1985 28.90792291220557 1986 28.28054298642534 1987 31.98294243070362 1988 33.47022587268994 1989 28.095238095238095 1990 27.900552486187845 1991 27.184466019417474 1992 45.69620253164556 1993 58.71446229913474 1994 49.69325153374233 1995 62.30677764565991 1996 57.58266818700114 1997 58.48214285714285 1998 57.61099365750527 1999 56.46817248459959 2000 56.28192032686415 2001 56.5749235474006 2002 56.770310932798395 2003 57.78210116731517 2004 44 2005 41.73151750972763 2006 31.26064735945485 2007 31.659574468085104 2008 28.55670103092784 2009 38 2010 41.125541125541126 2011 40.08207934336526 2012 40.46579330422125 2013 36.202185792349724 2014 35.425383542538356