Year	% of total fuel combustion
1960	27.13815241231725
1961	26.190113867183623
1962	25.655615325850246
1963	25.959255130969982
1964	26.686661045678786
1965	26.564977326400054
1966	26.466493653862315
1967	27.896693317440516
1968	26.87614900937806
1969	25.361383553165894
1970	22.864681723945985
1971	20.934523706635787
1972	20.287953292035326
1973	20.517922781416686
1974	20.003452302381074
1975	17.85101437024514
1976	17.824446850936464
1977	18.339929643644865
1978	17.71073554228629
1979	19.038180260209295
1980	19.013174941699383
1981	18.732930831881358
1982	16.71805507449017
1983	15.37844223213292
1984	16.123954746679782
1985	15.888667457299702
1986	15.473225980905221
1987	15.32001964640449
1988	15.155070103304139
1989	14.107878384293361
1990	13.034161437158774
1991	12.379904019775402
1992	11.227186790427238
1993	11.265108543384796
1994	11.18894434455914
1995	10.217327135197001
1996	9.958367002775534
1997	10.002246816159374
1998	10.016306245529343
1999	9.746958973745288
2000	10.546842653044987
2001	10.083861797328264
2002	9.398036428547815
2003	9.221926878934028
2004	9.57387401450621
2005	8.822977706878723
2006	9.282083261233671
2007	8.980791720735011
2008	8.943144486635495
2009	8.272063391757225
2010	8.983125883294454
2011	9.223043339812179
2012	9.14222090527885
2013	8.962751466519482
2014	8.983582300502006