Year	% of total fuel combustion
1960	1.721279500682661
1961	1.6958654519971992
1962	1.5912305516265932
1963	1.6549495655211555
1964	1.631966351209254
1965	1.6106014271151885
1966	1.6167379933428434
1967	1.544165424454383
1968	1.6036529680365281
1969	1.6168478260869565
1970	1.7405746553728616
1971	7.192638115769491
1972	7.197545099044027
1973	7.433965321665856
1974	7.032271886698841
1975	6.98212461695608
1976	6.751462016661656
1977	6.6703978607820416
1978	6.67799824802501
1979	7.044695632522491
1980	6.3961195938674615
1981	6.7012513860288285
1982	6.545556952942356
1983	6.520789869487167
1984	6.267611077147937
1985	6.256919088777494
1986	6.203122166724366
1987	6.169635337055871
1988	6.104252197240297
1989	5.3045368357767195
1990	5.518971928785335
1991	5.387187239178831
1992	4.765261784521627
1993	5.1106981186579645
1994	4.751100367868918
1995	4.446665366614664
1996	3.4400194662989705
1997	3.9411732893695337
1998	3.784565393988626
1999	3.92757398864764
2000	2.8957843672594037
2001	2.8581097428390296
2002	2.821810731598498
2003	2.8403413124723724
2004	2.751844423360307
2005	2.642198502855068
2006	2.548600652969638
2007	2.4816511386405087
2008	2.3269977728623656
2009	2.3123154187600248
2010	2.19199990390481
2011	2.0467691817385067
2012	2.1241966119056186
2013	2.105415437327496
2014	2.1183119007870985