Year	% of total fuel combustion
1971	2.701624962615891
1972	2.698608086355458
1973	2.7393796358732296
1974	2.8044871794871793
1975	2.714407238419303
1976	2.600506044419454
1977	2.8386321132781185
1978	2.5836329291328988
1979	2.6419213973799125
1980	2.401865912361669
1981	2.2820873104317068
1982	2.642946723024757
1983	3.1781161473087822
1984	3.241244289754188
1985	2.6963063139210552
1986	2.8564393006648614
1987	3.957594356542187
1988	3.8546845124282982
1989	2.9537857869495707
1990	4.033555504481728
1991	4.385408863020803
1992	3.383479671159331
1993	2.7949309993019376
1994	2.42944849938078
1995	2.5344915687276446
1996	2.3336299812123014
1997	2.0025810019818415
1998	3.0449516595235724
1999	2.8978584507602894
2000	2.820260634374231
2001	2.686862186264595
2002	2.239132941312118
2003	2.265895427218073
2004	2.187734557817122
2005	2.844793549861813
2006	2.863328592957358
2007	3.3860683742084308
2008	2.7861972487759386
2009	1.7610444815545772
2010	2.1727197067625235
2011	2.044010680416168
2012	2.3819716766272236
2013	2.6509598008796753
2014	2.627871876572195