Year	% of total fuel combustion
1971	1.9782732990280156
1972	2.4713429382690086
1973	2.811244979919678
1974	2.8573774529928553
1975	2.979084664660028
1976	3.1177909821740655
1977	3.43067183990198
1978	3.2110951458736805
1979	3.6788114609126286
1980	4.3289010792439315
1981	4.4479999999999995
1982	4.8204340311119624
1983	5.436395521381359
1984	5.4316328593571
1985	6.018696375976437
1986	5.333943799004178
1987	5.80429328129356
1988	5.952315702932311
1989	6.214107703976595
1990	6.002713704206242
1991	5.513417377203536
1992	5.758520259567727
1993	5.899457861015278
1994	6.012357414448669
1995	5.985420692077992
1996	5.785728806668023
1997	6.084344221774346
1998	5.2553773375711454
1999	5.231726505507081
2000	4.854435359720846
2001	5.212968849332484
2002	5.1012878991145705
2003	5.225718194254446
2004	4.919779191012688
2005	4.847020933977453
2006	4.827564245454257
2007	4.881082392913481
2008	5.1481790221046895
2009	5.360996362291141
2010	4.906485304833618
2011	4.530403757796658
2012	4.3482379689276245
2013	4.072408215717989
2014	4.046048485357759