Year	% of total fuel combustion
1971	30.76923076923077
1972	26.506024096385545
1973	30.379746835443033
1974	30.136986301369863
1975	29.230769230769234
1976	25.675675675675674
1977	24.358974358974358
1978	21.73913043478261
1979	22.471910112359552
1980	27.272727272727277
1981	23.893805309734518
1982	24.031007751937985
1983	29.896907216494846
1984	22.55639097744361
1985	12.06896551724138
1986	24.06417112299465
1987	22.95918367346939
1988	21.02803738317757
1989	19.396551724137932
1990	19.480519480519483
1991	23.076923076923077
1992	24.423963133640555
1993	20.99644128113879
1994	23.50597609561753
1995	28.99159663865546
1996	23.27586206896552
1997	30.364372469635626
1998	27.42616033755274
1999	24.896265560165972
2000	21.5962441314554
2001	17.26907630522088
2002	12.5
2003	13.793103448275861
2004	17.307692307692307
2005	11.76470588235294
2006	13.513513513513514
2007	12.363636363636363
2008	20.930232558139537
2009	18.623481781376515
2010	21.011673151750976
2011	20.622568093385215
2012	19.62962962962963
2013	22.362869198312236
2014	23.07692307692308