Year	% of total fuel combustion
1971	5.5383423702556165
1972	5.3388802218755425
1973	5.113996200126662
1974	4.774324422227052
1975	4.320136563587421
1976	4.306777784253161
1977	4.024925937276534
1978	3.8823119777158768
1979	3.866401081311802
1980	3.5570696375410487
1981	3.0575238520336994
1982	2.9367011564211802
1983	3.162277213827946
1984	3.580444197410779
1985	2.7155057379236722
1986	2.968943838179945
1987	2.982917994497338
1988	3.3526505442252676
1989	3.151204872451231
1990	1.5556234169825218
1991	1.8169703954476701
1992	1.4345369688037337
1993	1.2119649303764826
1994	1.001547455295736
1995	1.202303714810196
1996	1.0877623367345564
1997	1.0910300193136617
1998	1.1145116041826066
1999	1.119586459055664
2000	1.0916203166065641
2001	1.2357392715882851
2002	1.0982493904715884
2003	1.1506164398196619
2004	1.2082028487726033
2005	1.53267512929008
2006	1.5133323776073402
2007	1.5640719180732423
2008	1.4759443339960239
2009	1.481795409310034
2010	1.3315092826037132
2011	1.2890307239847318
2012	1.1645013436553966
2013	1.1971041357452572
2014	1.1174157582997362