Year	% of total fuel combustion
1971	8.053691275167786
1972	7.8431372549019605
1973	7.185628742514972
1974	6.521739130434782
1975	7.027027027027027
1976	6.60377358490566
1977	5.747126436781611
1978	6.382978723404256
1979	7.792207792207792
1980	7.18232044198895
1981	7.407407407407408
1982	8.02139037433155
1983	7.6530612244897975
1984	7.82122905027933
1985	8.287292817679559
1986	8.450704225352112
1987	7.87037037037037
1988	7.8125
1989	7.602339181286551
1990	7.065217391304348
1991	6.593406593406594
1992	6.132075471698113
1993	6.220095693779905
1994	7.949790794979079
1995	5.976095617529882
1996	6.390977443609022
1997	5.944055944055944
1998	5.059523809523809
1999	5.899705014749262
2000	5.932203389830508
2001	4.8517520215633425
2002	5.221932114882507
2003	5.063291139240507
2004	8.04878048780488
2005	7.94044665012407
2006	8.0188679245283
2007	6.651376146788992
2008	6.205250596658711
2009	8.153477218225419
2010	8.644859813084112
2011	8.501118568232663
2012	8.803611738148986
2013	11.032863849765258
2014	11.013215859030836