Year	% of total fuel combustion
1960	2.6132538762897974
1961	2.556887493697239
1962	2.6755594335928103
1963	2.7204759408265144
1964	2.585385126745016
1965	2.742057319268744
1966	2.754984937598624
1967	2.6602681636333068
1968	2.77974197597905
1969	2.745064229674972
1970	2.0172421019007998
1971	2.5534794172013546
1972	2.4940231717035495
1973	2.5121868488636925
1974	2.5654340990267857
1975	2.7604142716268893
1976	2.6183070793842864
1977	2.5301392715535376
1978	2.560465427035473
1979	2.6956151740434957
1980	2.5248259008659053
1981	2.579964110558025
1982	2.4486053296402877
1983	2.5623096150909426
1984	2.157937302738954
1985	2.1996536039255647
1986	2.2151758691481986
1987	2.1932078577421343
1988	2.112428590074397
1989	2.0190615677482735
1990	1.8529284254795233
1991	1.8909152331613668
1992	1.698016291705251
1993	1.7249919299403216
1994	1.723442086620342
1995	1.7353944616320325
1996	1.7095776514771153
1997	1.6618678430388443
1998	1.5956752649271917
1999	1.550747516018201
2000	1.5188319354630129
2001	1.521759583353931
2002	1.5136293777887537
2003	1.3874548473046469
2004	1.4724902376445135
2005	1.5385890624685288
2006	1.5602045791965449
2007	1.4854872988875183
2008	1.5235498585478
2009	1.521244020181547
2010	1.5336318461678546
2011	1.4936993239793313
2012	1.4667418757283126
2013	1.4679266886312603
2014	1.4541231670769112