Year	% of total fuel combustion
1971	26.539603486256105
1972	26.721030042918454
1973	27.997513404304918
1974	26.600304161482097
1975	26.774587660354303
1976	26.332941553584785
1977	26.332731795347023
1978	27.265574377487734
1979	27.578035626736394
1980	29.225210758731436
1981	29.093944452876006
1982	29.597089711030275
1983	30.940222288975672
1984	30.831831493579635
1985	30.581178352439352
1986	33.39383417508417
1987	32.65092387103209
1988	34.18329371653581
1989	33.25308253082531
1990	32.942254012561065
1991	32.40041710114703
1992	33.12504777191776
1993	36.34514293943976
1994	36.708543553075614
1995	36.84475724525787
1996	36.51503931176832
1997	38.52199864078243
1998	36.47114330938755
1999	35.717848654675635
2000	35.5082514790387
2001	36.38475836431227
2002	37.03068592057762
2003	38.03625491501577
2004	38.305280120446504
2005	37.491567471111786
2006	37.21039155686005
2007	35.93559842786745
2008	38.12395567249889
2009	39.38118290886129
2010	40.081494732657525
2011	40.22863266946503
2012	41.256415130203386
2013	41.81148598194284
2014	42.711549068517286