Year	% of total fuel combustion
1971	31.899921813917125
1972	33.28038125496426
1973	35.944700460829495
1974	32.30466185160867
1975	31.893892658852558
1976	31.104815864022665
1977	29.65714285714286
1978	26.286008230452673
1979	26.448942042318308
1980	26.973406500633175
1981	27.06114398422091
1982	27.44728915662651
1983	28.65874363327674
1984	29.01399067288475
1985	27.872340425531917
1986	30.312403340550574
1987	30.773791876667662
1988	31.82837913628716
1989	29.804015296367115
1990	29.340592861464003
1991	26.130485566494244
1992	26.629570747217805
1993	25.73073516386183
1994	26.38070439906811
1995	25.725776046248587
1996	25.72340191440202
1997	27.685822966999073
1998	25.744702630770806
1999	28.592927012791574
2000	27.992697557159
2001	29.025828419566484
2002	28.307108405155372
2003	28.705935522747815
2004	27.944588508257134
2005	26.115140234901478
2006	24.102120294244916
2007	23.323222109875292
2008	22.920060965995688
2009	25.175237085468577
2010	23.226044355475953
2011	23.305129008670217
2012	23.119979269240737
2013	27.98985840030616
2014	29.711590785416288