Year	% of total fuel combustion
1960	2.6132538762897974
1961	2.556887493697239
1962	2.675559433592811
1963	2.7204759408265144
1964	2.585385126745017
1965	2.742057319268744
1966	2.754984937598624
1967	2.6602681636333068
1968	2.7797419759790496
1969	2.745064229674972
1970	2.0172421019007998
1971	3.41799739035908
1972	3.356644177768534
1973	3.408856276107433
1974	3.42388762164413
1975	3.654366454259847
1976	3.502722406158269
1977	3.4466195015467544
1978	3.517003624023204
1979	3.7080030351318602
1980	3.4897283053531787
1981	3.590592882926819
1982	3.5090834685257453
1983	3.6422821608700633
1984	3.3605964813813016
1985	3.3270908818561407
1986	3.281546777693922
1987	3.2687361605663585
1988	3.1688985767535995
1989	2.915902234465529
1990	3.650809574244454
1991	3.6169412661325095
1992	3.2083756508842356
1993	3.2594626613370434
1994	3.1095634062452615
1995	2.807347018003591
1996	2.458013547986451
1997	2.55797251117203
1998	2.438357302446758
1999	2.477168573330181
2000	2.161070175793407
2001	2.1761890319117803
2002	2.1422134537671162
2003	2.1034785544861396
2004	2.173355548193078
2005	2.1948921406094484
2006	2.165298269724679
2007	2.0928600217109716
2008	2.082514159432044
2009	2.156132806577
2010	2.0544412930601688
2011	1.902708564727167
2012	1.9788303677943353
2013	1.9512671340372014
2014	1.955232493576169