Year	% of total fuel combustion
1971	26.153846153846157
1972	21.052631578947366
1973	25.595238095238095
1974	24.85207100591716
1975	22.916666666666668
1976	23.58974358974359
1977	25.37313432835821
1978	27.722772277227726
1979	29.896907216494846
1980	30
1981	28.666666666666668
1982	25.675675675675674
1983	24.832214765100673
1984	25
1985	21.341463414634145
1986	22.839506172839506
1987	20.5
1988	23.923444976076556
1989	24.01960784313725
1990	23.696682464454977
1991	19.855595667870038
1992	23.02839116719243
1993	20.56338028169014
1994	19.070904645476773
1995	17.286652078774615
1996	17.33668341708543
1997	18.8911704312115
1998	19.385796545105567
1999	20.155038759689923
2000	20.502901353965186
2001	20.145190562613433
2002	20.795660036166364
2003	19.79695431472081
2004	19.05564924114671
2005	18.88
2006	17.791411042944784
2007	19.79768786127168
2008	16.286644951140065
2009	13.957307060755337
2010	14.604810996563572
2011	15.307820299500833
2012	19.102990033222593
2013	11.169284467713785
2014	11.904761904761903