Year	% of total fuel combustion
1971	39.473684210526315
1972	44.44444444444445
1973	43.24324324324324
1974	48.78048780487806
1975	41.463414634146346
1976	47.36842105263159
1977	42.37288135593221
1978	42.1875
1979	35.38461538461539
1980	33.87096774193548
1981	15.384615384615385
1982	29.850746268656714
1983	33.33333333333333
1984	33.33333333333333
1985	33.75
1986	24.324324324324323
1987	23.456790123456788
1988	24.719101123595504
1989	21.50537634408602
1990	19.35483870967742
1991	24.719101123595504
1992	27.160493827160494
1993	20
1994	10.526315789473683
1995	15.555555555555555
1996	15.09433962264151
1997	19.685039370078737
1998	23.846153846153843
1999	25.925925925925924
2000	18.11594202898551
2001	16.55629139072848
2002	25.43352601156069
2003	26.21951219512195
2004	19.047619047619047
2005	19.191919191919194
2006	19.306930693069308
2007	21.98275862068966
2008	21.98275862068966
2009	20.535714285714285
2010	25.35885167464115
2011	25.700934579439256
2012	16.826923076923077
2013	22.119815668202765
2014	24.637681159420293