Year	% of total fuel combustion
1971	18.75
1972	14.655172413793105
1973	14.173228346456693
1974	14.399999999999999
1975	13.533834586466165
1976	16.901408450704224
1977	18.987341772151897
1978	11.39240506329114
1979	10.11904761904762
1980	13.529411764705884
1981	14.285714285714285
1982	15.723270440251572
1983	14.204545454545455
1984	13.440860215053762
1985	7.784431137724551
1986	4.11764705882353
1987	4.736842105263158
1988	3.8277511961722492
1989	3.017241379310345
1990	2.293577981651376
1991	1.3888888888888888
1992	4.471544715447155
1993	6.153846153846153
1994	10.666666666666668
1995	25.210084033613445
1996	20.738636363636363
1997	24.03314917127072
1998	30.555555555555554
1999	19.266055045871557
2000	23.16258351893096
2001	24.57466918714556
2002	26.334519572953734
2003	25.801282051282055
2004	32.57467994310099
2005	32.262569832402235
2006	25.156250000000004
2007	33.00492610837439
2008	34.263959390862944
2009	30.945945945945947
2010	30.79019073569482
2011	34.60620525059666
2012	21.91616766467066
2013	25.917159763313613
2014	40.91428571428571