Year	% of total fuel combustion
1971	4.498816101026045
1972	4.649548924358085
1973	4.100227790432802
1974	3.8118811881188117
1975	3.776099511328298
1976	3.5521235521235526
1977	2.6430438571013655
1978	1.8928639030853682
1979	1.466992665036675
1980	1.5089025248968917
1981	1.3280212483399734
1982	1.379915450267209
1983	1.253430245494326
1984	1.355961112058673
1985	1.3669553404652743
1986	1.4350835725139288
1987	1.1753860336483062
1988	1.2938200216841345
1989	1.24628650097819
1990	1.6812284882181623
1991	1.9139060214917019
1992	1.582463954987692
1993	1.6096023010122245
1994	1.5650101051976992
1995	1.5342866089134746
1996	1.4841024128949825
1997	1.4877479579929989
1998	1.430712631148658
1999	1.4108177435761353
2000	1.4238819968452914
2001	1.4145399597044996
2002	1.3672334090731022
2003	1.3595222894054908
2004	1.3225074457523756
2005	1.3558866962008325
2006	1.2477493129481632
2007	1.2398679075352745
2008	1.1917838312829525
2009	1.154454401686874
2010	1.0522548317823908
2011	1.1805044182621502
2012	0.9971079552812191
2013	0.9086277173913044
2014	0.8211768886081448