Year	% of total fuel combustion
1971	6.097560975609756
1972	13.178294573643413
1973	16.408668730650156
1974	20.771513353115726
1975	20.528455284552845
1976	22.448979591836736
1977	21.79245283018868
1978	25.63265306122449
1979	28.08833678398896
1980	27.263267429760667
1981	25.675096442348906
1982	28.79499217527387
1983	33.21182665046577
1984	28.136762860727732
1985	27.512633352049416
1986	25.987006496751626
1987	24.920850293984625
1988	26.292629262926287
1989	24.090821627862226
1990	26.315789473684216
1991	23.516483516483515
1992	26.366047745358088
1993	28.796777982883032
1994	28.76315388134818
1995	29.00631820792648
1996	29.555769495255124
1997	30.38486627527723
1998	32.59788292309654
1999	34.89641483686887
2000	38.83251910309408
2001	36.95417207090358
2002	40.04654114660461
2003	42.391414397084134
2004	47.566434898561766
2005	47.997479974799745
2006	49.46965745087811
2007	45.90414820781313
2008	46.55925723648281
2009	40.34013605442176
2010	40.05271828665568
2011	38.682920698755815
2012	39.88816951147734
2013	39.107626678964664
2014	41.520834520891526