Year	% of total fuel combustion
1971	21.09746930593836
1972	21.883468834688347
1973	20.843776106934
1974	20.619182517199512
1975	21.455648218347232
1976	22.130059721300594
1977	21.367388257280794
1978	21.840044742729308
1979	22.94195250659631
1980	21.54566744730679
1981	19.94142055162314
1982	19.208449396471682
1983	23.558573122103677
1984	24.599220103986138
1985	25.585149313962873
1986	28.097237137557354
1987	27.593797856049008
1988	27.241500792672184
1989	26.81268882175227
1990	25.429155919238635
1991	26.099679063620915
1992	33.24968632371393
1993	41.17415803957542
1994	44.7080979284369
1995	43.78459989934575
1996	41.95151152349596
1997	46.64854125274495
1998	37.06500328299409
1999	28.276159035452842
2000	31.07333719657459
2001	32.08020050125313
2002	31.003626155105856
2003	32.17088570248421
2004	32.283331454975766
2005	31.457589898435355
2006	31.100291023057984
2007	28.31889081455806
2008	31.871360098953776
2009	38.621931570467254
2010	38.496849309351916
2011	37.321736404952205
2012	37.65436530729466
2013	39.743851761019144
2014	44.843462246777165