Year	% of total fuel combustion
1971	24.755700325732903
1972	24.525745257452574
1973	26.420217209690897
1974	25.657628490489678
1975	24.336618650492795
1976	24.70139349701394
1977	21.756735710948448
1978	19.770693512304252
1979	19.221635883905012
1980	17.72463946752126
1981	18.15962899682695
1982	18.744196843082634
1983	16.575061967884473
1984	15.901213171577123
1985	16.58595641646489
1986	15.25920140583813
1987	14.701378254211333
1988	15.906288532675708
1989	16.05404498153743
1990	16.881615227252514
1991	16.311119501604683
1992	14.525057199793341
1993	13.287904599659287
1994	12.799748901443818
1995	12.40563663814796
1996	12.09218796767435
1997	10.253058663599289
1998	12.344057780695989
1999	14.260083249605284
2000	12.99336810250467
2001	11.995104039167687
2002	11.785004094046089
2003	12.904938927243759
2004	12.008339907584809
2005	10.930551743068897
2006	11.428251623013207
2007	13.17735413056037
2008	11.091068391485853
2009	9.800018955549236
2010	9.514668447189417
2011	11.757561510734995
2012	12.21280873061459
2013	11.151985830097416
2014	10.638647724283082