Year	% of total fuel combustion
1971	5.737490175530522
1972	5.870342011230219
1973	5.866666666666666
1974	6.135799684186782
1975	5.851063829787234
1976	5.841852701856874
1977	6.496891918989372
1978	6.151107594936709
1979	6.6169617893755825
1980	6.525636428827537
1981	6.462464589235127
1982	7.1077184054283284
1983	9.923785328675772
1984	10.564997703261369
1985	8.605295566502464
1986	9.986878553725033
1987	12.882832256251758
1988	12.816030123722431
1989	11.055750067331
1990	19.84882169853268
1991	20.250766732816164
1992	18.23367427222659
1993	15.659109991603692
1994	10.951882845188283
1995	9.874069834001144
1996	9.141224781289056
1997	8.372601817569844
1998	9.487219695781716
1999	10.083333333333334
2000	8.343427146419666
2001	9.19220055710306
2002	8.077044521629302
2003	8.19455299705405
2004	8.027535984525233
2005	7.683172406671142
2006	7.701002555533714
2007	7.692660971801231
2008	7.703546287687606
2009	5.526544821583986
2010	5.098072017063276
2011	5.268163585990159
2012	5.524050426339194
2013	6.121319897253507
2014	6.158157854870474