Year	% of total fuel combustion
1971	83.33333333333334
1972	80
1973	78.04878048780488
1974	78.57142857142858
1975	78.26086956521738
1976	64.28571428571428
1977	69.6969696969697
1978	71.05263157894737
1979	71.05263157894737
1980	66.66666666666666
1981	60
1982	66.66666666666666
1983	63.88888888888889
1984	73.6842105263158
1985	76.59574468085107
1986	78.04878048780488
1987	77.77777777777779
1988	75.00000000000001
1989	67.85714285714285
1990	65.38461538461539
1991	65
1992	57.14285714285714
1993	57.14285714285714
1994	54.54545454545454
1995	54.54545454545454
1996	54.94505494505494
1997	58.62068965517242
1998	61.98347107438017
1999	63.43283582089552
2000	64.7887323943662
2001	57.22543352601156
2002	57.920792079207914
2003	60.087719298245624
2004	57.61316872427983
2005	57.46268656716418
2006	60.493827160493815
2007	64.1160949868074
2008	63.968668407310716
2009	67.06443914081144
2010	69.67032967032966
2011	69.65811965811966
2012	69.59183673469389
2013	69.59847036328871
2014	67.59581881533101