Year	% of total fuel combustion
1971	16.666666666666668
1972	19.148936170212767
1973	18.0327868852459
1974	10.714285714285712
1975	10.526315789473683
1976	9.401709401709404
1977	3.787878787878788
1978	2.873563218390805
1979	7.518796992481203
1980	9.30232558139535
1981	7.4074074074074066
1982	6.8181818181818175
1983	13.186813186813188
1984	8.609271523178808
1985	14.285714285714285
1986	16.216216216216218
1987	19.53125
1988	17.36111111111111
1989	26.54867256637169
1990	34.065934065934066
1991	29.906542056074763
1992	28.828828828828833
1993	27.499999999999996
1994	21.551724137931036
1995	25.190839694656486
1996	29.787234042553195
1997	27.631578947368425
1998	30.246913580246908
1999	30.263157894736846
2000	30.821917808219183
2001	27.7027027027027
2002	32.60869565217392
2003	35.97122302158274
2004	36.36363636363637
2005	36.41618497109826
2006	33.888888888888886
2007	39.69072164948454
2008	34
2009	33.49514563106796
2010	30.075187969924812
2011	30.76923076923077
2012	30.914826498422716
2013	28.613569321533927
2014	32.664756446991404