Year	% of total fuel combustion
1960	3.85971600114362
1961	3.7046806378011947
1962	4.0238404429961045
1963	4.313536133912763
1964	3.7877612535738816
1965	3.955973419899298
1966	3.989549572010306
1967	3.902661365880834
1968	4.0103837321529605
1969	3.83791086681952
1970	2.8352082129483
1971	4.162810709009141
1972	4.331670393944607
1973	4.4329325576639835
1974	4.300012912951691
1975	4.655633233169193
1976	4.635991673246716
1977	4.731185276399155
1978	4.759521406306915
1979	5.040087336478806
1980	5.07412238602709
1981	5.131030929310566
1982	5.113024915623506
1983	5.155491545313918
1984	3.939940997754391
1985	3.990881308718295
1986	3.9245870448845466
1987	4.057669102747989
1988	3.532635147128715
1989	2.847913093196112
1990	2.79626129508324
1991	2.7882851319565383
1992	2.6723361710969713
1993	2.7789008134862296
1994	2.837621890577901
1995	2.8410072662125665
1996	2.8102514017426916
1997	2.820278602420644
1998	2.797561100578982
1999	2.6614021524377525
2000	2.638791490456315
2001	2.5240352064996614
2002	2.468309593790037
2003	2.1959325673285357
2004	2.2229650676917934
2005	2.4111532808801743
2006	2.3366690451058214
2007	2.2515954776872147
2008	2.2763930177605003
2009	2.240514520150179
2010	2.2783372985246944
2011	2.163634800663902
2012	2.1585647366929015
2013	2.178151538888908
2014	2.198644695964973