Year	% of total fuel combustion
1960	1.598029969611234
1961	1.6171965245341793
1962	1.463761250592139
1963	1.5555451436068024
1964	1.5519263737255262
1965	2.5187032418952615
1966	2.564459445353005
1967	2.3607400142050268
1968	2.4371146129000665
1969	2.3971769286931126
1970	2.5177095631641087
1971	8.189877117051925
1972	8.186032641110447
1973	8.597745538044046
1974	7.841734888057319
1975	8.08075888018899
1976	8.071350228020552
1977	7.891358243315032
1978	8.090353808920135
1979	8.929667990338558
1980	8.449331424568246
1981	8.06443128136606
1982	7.569933357010048
1983	7.503444820243017
1984	6.777295444516281
1985	6.906940302279734
1986	6.439079368845651
1987	6.70454982500673
1988	5.707905053539039
1989	3.823627254306999
1990	3.646296012661459
1991	3.487186308415358
1992	3.0371784252289897
1993	3.5894780958015926
1994	3.752891238593904
1995	3.376406836181742
1996	2.833323116532826
1997	3.0681141612090044
1998	3.0409325166617203
1999	3.1838040033122974
2000	3.1300578034682087
2001	2.848218088882578
2002	2.7321139152581626
2003	2.623894601364536
2004	2.6357816384063106
2005	2.7518591761134172
2006	2.4146874146874158
2007	2.2642738848315362
2008	2.370366253543045
2009	2.406280902580085
2010	2.415828438659029
2011	2.4142863334922637
2012	2.5104917194386367
2013	2.57583090060415
2014	2.6345599896430074