Year	% of total fuel combustion
1960	17.16475095785441
1961	18.201595358955764
1962	19.784172661870503
1963	19.3570929419986
1964	21.418918918918916
1965	22.829131652661065
1966	21.719745222929937
1967	23.09958750736594
1968	19.484702093397747
1969	21.15583075335397
1970	22.955010224948875
1971	24.72273567467652
1972	24.263674614305753
1973	23.102785782901055
1974	23.151837096060206
1975	20.76631977294229
1976	20.11888431641518
1977	20.01703577512777
1978	18.275862068965516
1979	21.153846153846153
1980	22.363847045191193
1981	22.654729466718567
1982	21.290067273446773
1983	20.70063694267516
1984	23.052208835341368
1985	21.928166351606805
1986	18.5360524399126
1987	20.103092783505154
1988	18.185053380782918
1989	18.37153609305508
1990	13.251411491198938
1991	13.313802083333334
1992	12.325656827765163
1993	12.778315585672798
1994	12.983770287141075
1995	12.93288384921851
1996	11.801059446733372
1997	12.489282652186338
1998	11.542553191489361
1999	11.636828644501279
2000	12.956159686505023
2001	12.174115456238361
2002	11.763307984790876
2003	12.38980223969502
2004	12.647475224162342
2005	12.432188065099457
2006	12.364521123645211
2007	11.023622047244094
2008	11.262488646684831
2009	9.346504559270517
2010	9.05161454360539
2011	10.363429869392391
2012	10.030820958251612
2013	10.25864574251671
2014	10.572947430596574