Year	% of total fuel combustion
1971	40.804597701149426
1972	32.603938730853386
1973	33.909287257019436
1974	33.4
1975	33.589251439539346
1976	33.831775700934585
1977	32.3943661971831
1978	30.7032590051458
1979	31.38211382113821
1980	28.278041074249604
1981	25.166666666666664
1982	25.561312607944732
1983	25.77777777777778
1984	27.82485875706215
1985	31.621187800963078
1986	29.7029702970297
1987	32.54950495049505
1988	28.290282902829023
1989	35.75547866205306
1990	31.216216216216214
1991	29.648894668400516
1992	27.13178294573644
1993	29.654403567447048
1994	29.745042492917843
1995	31.283422459893046
1996	32.36272878535774
1997	32.53099927060539
1998	29.64376590330789
1999	29.53864589574595
2000	32.221006564551416
2001	28.60347728547392
2002	31.057842626367897
2003	29.8871063576946
2004	39.06048906048906
2005	33.71824480369515
2006	30.881557598702003
2007	30.36677454153182
2008	27.99145299145299
2009	29.54298150163221
2010	30.933750652060503
2011	31.340206185567016
2012	33.149448345035104
2013	28.897917724733368
2014	26.323987538940806