Year	% of total fuel combustion
1971	11.698250728862975
1972	11.069095909247164
1973	9.90581357583631
1974	9.549492385786802
1975	10.66358534169693
1976	9.740467798782442
1977	10.028836911246396
1978	10.076804915514593
1979	9.591474245115453
1980	10.477990818255469
1981	10.601001669449081
1982	10.605637733742673
1983	9.812449035063876
1984	11.008174386920983
1985	10.92606611153167
1986	10.763636363636364
1987	11.345258515069835
1988	11.630036630036628
1989	12.27911191662891
1990	11.540130151843817
1991	11.091549295774648
1992	11.620400258231115
1993	12.138979370249729
1994	12.52517116391462
1995	12.538699690402476
1996	14.092632272952034
1997	14.279210925644918
1998	14.145616641901933
1999	13.199505018561807
2000	12.888542073091429
2001	13.266523502743976
2002	13.65284387038296
2003	13.99117858241871
2004	13.261959876543209
2005	12.275394206087276
2006	12.326775021385801
2007	12.007025387194634
2008	11.929718724078125
2009	12.493882402293226
2010	12.31694560669456
2011	11.84094070046782
2012	11.57925925925926
2013	11.531618955199743
2014	10.891783567134267