Year	% of total fuel combustion
1971	36.8421052631579
1972	44.44444444444445
1973	48.648648648648646
1974	43.90243902439025
1975	48.78048780487806
1976	43.85964912280702
1977	45.76271186440678
1978	45.31249999999999
1979	47.692307692307686
1980	48.387096774193544
1981	59.61538461538461
1982	44.776119402985074
1983	40
1984	38.46153846153846
1985	37.49999999999999
1986	43.24324324324324
1987	41.9753086419753
1988	41.57303370786517
1989	44.08602150537634
1990	46.236559139784944
1991	44.943820224719104
1992	50.61728395061728
1993	58.46153846153847
1994	57.89473684210527
1995	55.55555555555556
1996	52.83018867924528
1997	45.669291338582674
1998	49.230769230769226
1999	48.888888888888886
2000	51.44927536231884
2001	51.65562913907284
2002	47.398843930635834
2003	48.170731707317074
2004	59.25925925925927
2005	58.080808080808076
2006	58.415841584158414
2007	57.32758620689656
2008	57.32758620689656
2009	58.48214285714285
2010	51.674641148325364
2011	51.40186915887851
2012	46.15384615384615
2013	41.474654377880185
2014	42.391304347826086