Year	% of total fuel combustion
1960	3.931115994140365
1961	3.7015247735405046
1962	4.0574879299263085
1963	4.35364663226886
1964	3.6959853720186073
1965	3.6874225608309383
1966	3.69515919726304
1967	3.5542429411614935
1968	3.676549479632345
1969	3.472882442680581
1970	2.5646087663157497
1971	2.8958732038912185
1972	3.143425129598467
1973	3.151815641901453
1974	3.1989506044989193
1975	3.447583744725918
1976	3.4150839165563807
1977	3.516381945401624
1978	3.608715388107126
1979	3.67856632549465
1980	3.7217540285238013
1981	3.911797934151065
1982	4.025419297078621
1983	4.152628460171
1984	2.75853953738569
1985	2.872129442890747
1986	2.927109479389104
1987	2.9831532300989023
1988	2.6772712459418098
1989	2.458482249466735
1990	2.468409304004299
1991	2.531285662539387
1992	2.513309297638453
1993	2.4925587622365892
1994	2.5065833189771864
1995	2.622070941161324
1996	2.7697783784420875
1997	2.6847585387089468
1998	2.6648449519842456
1999	2.458838607906931
2000	2.449770884737399
2001	2.384660045601529
2002	2.3360218560783377
2003	2.0267960771204163
2004	2.062657813522865
2005	2.271429644654797
2006	2.2713520709164072
2007	2.2046518768711136
2008	2.201778931078145
2009	2.1457199510610483
2010	2.190397683698536
2011	2.045322038548597
2012	2.0195397307859326
2013	2.0291404538064612
2014	2.0505675761599313