Year	% of total fuel combustion
1971	15.12445585444804
1972	15.108459869848158
1973	14.772846500891829
1974	14.53691677490259
1975	14.192480031170856
1976	14.338903014892841
1977	14.657783161720166
1978	14.554652512854535
1979	14.117557135213637
1980	14.171916865812152
1981	15.075800112296461
1982	14.77454642475987
1983	15.784165405950578
1984	15.948670944087992
1985	15.478615071283096
1986	16.03892593260047
1987	16.402245545521115
1988	16.427640156453716
1989	14.761648423948799
1990	14.725487819658222
1991	15.403195837978446
1992	15.257703845104993
1993	15.435848642318668
1994	14.385538508278898
1995	15.11403169694627
1996	14.380674448767833
1997	13.916146297948261
1998	13.99376231122784
1999	14.621940730315115
2000	13.975707302621839
2001	14.348255896059879
2002	13.415929203539823
2003	13.544295164700266
2004	13.11636435073014
2005	12.84734539434788
2006	12.746043451131657
2007	12.075718015665796
2008	12.023460410557183
2009	9.851641940323386
2010	9.277819139797261
2011	7.815120413228684
2012	8.414357774691132
2013	7.671188630490956
2014	9.03994947102479