Year	% of total fuel combustion
1971	6.166107382550337
1972	5.72980312287848
1973	5.9303932654856135
1974	5.733999524149417
1975	5.6822048315753655
1976	5.52199258081611
1977	5.8188362327534495
1978	5.462463315346019
1979	5.729729729729731
1980	5.6008655126498
1981	5.008745428525997
1982	5.213903743315507
1983	6.088495575221239
1984	6.166943521594685
1985	5.448271285420399
1986	5.738019169329074
1987	7.179336659818022
1988	7.000056000448004
1989	6.078548536042153
1990	25.882877526753866
1991	25.638802173661688
1992	22.656934306569344
1993	22.74122159929183
1994	22.030139150513463
1995	6.674225020139035
1996	5.556980422330513
1997	5.051194539249146
1998	5.9870550161812295
1999	5.480596721472631
2000	5.143772259005186
2001	5.230973593202482
2002	4.705621465794433
2003	4.5826406509755895
2004	4.534205779958893
2005	4.472430774198757
2006	4.785333567621391
2007	4.930260311777429
2008	4.777728548220351
2009	3.78574380941645
2010	4.118993135011442
2011	3.940541298555602
2012	4.372131543531523
2013	4.7704708202165556
2014	4.668524617853221