Year	% of total fuel combustion
1971	8.680555555555555
1972	8.680555555555555
1973	6.744868035190615
1974	12.853470437017995
1975	14.058956916099774
1976	14.102564102564106
1977	13.333333333333334
1978	12.909441233140656
1979	14.912280701754385
1980	15.045592705167174
1981	13.029827315541601
1982	14.244186046511627
1983	17.107309486780718
1984	16.744913928012522
1985	17.532467532467532
1986	15.492957746478876
1987	15.106382978723405
1988	15.368852459016393
1989	15.633937082936129
1990	14.623467600700524
1991	17.02325581395349
1992	17.97274275979557
1993	17.373899119295437
1994	16.406829992576093
1995	16.20145631067961
1996	17.636472705458907
1997	17.716115261472787
1998	17.923036373220878
1999	15.760040671072698
2000	14.469914040114611
2001	15.257648953301128
2002	14.50640542577242
2003	14.141777617848147
2004	15.270770265724856
2005	15.805946791862285
2006	14.975845410628018
2007	14.450402144772118
2008	14.729630535845365
2009	14.421985010220304
2010	14.744232698094281
2011	16.084834834834837
2012	15.113438045375219
2013	13.724832214765101
2014	14.19624217118998