Year	% of total fuel combustion
1960	13.78497327884313
1961	13.354427201044647
1962	13.22595926101374
1963	13.38612191350794
1964	12.68609582243075
1965	11.457071606697543
1966	11.611399144020321
1967	11.509453106503871
1968	11.399301817232717
1969	10.817717206132878
1970	10.56965761511216
1971	8.14951918393476
1972	8.08572358076235
1973	7.996294750026092
1974	7.653993026730865
1975	7.622897918924513
1976	7.203140333660451
1977	6.966088188418629
1978	6.62042809098243
1979	6.310639865722357
1980	5.9019422700090365
1981	5.695077172346313
1982	5.436939854179288
1983	5.366612384650716
1984	5.273852406021982
1985	5.024515998584643
1986	5.224028156760391
1987	5.3286412061074575
1988	5.602582356497825
1989	6.422443774634825
1990	7.652014090978709
1991	7.56739381041057
1992	8.059927251773688
1993	7.893893449695535
1994	8.331850646874921
1995	8.369648969899073
1996	9.329982222767118
1997	10.178487731343662
1998	11.217991959202397
1999	12.19125667456669
2000	11.748554913294798
2001	12.383927303705809
2002	12.94570502431118
2003	13.210811110034738
2004	14.230165673735225
2005	15.118513773222295
2006	15.741195741195742
2007	16.850378736459156
2008	17.931973545267603
2009	18.697371969674265
2010	18.013363543215046
2011	18.07030471154263
2012	18.528602157007267
2013	18.38050486285652
2014	19.642683755704436