Year	% of total fuel combustion
1971	9.312638580931266
1972	11.161731207289293
1973	11.918604651162793
1974	10.945273631840799
1975	13.231552162849871
1976	17.661097852028636
1977	16.741071428571427
1978	17.45689655172414
1979	17.016806722689076
1980	18.343195266272186
1981	20.558882235528944
1982	22.718446601941743
1983	23.895582329317268
1984	26.642335766423354
1985	31.93717277486911
1986	33.003300330033
1987	44.56762749445676
1988	43.22429906542056
1989	43.062200956937794
1990	40.66496163682864
1991	42.03655352480418
1992	41.80929095354523
1993	40.86021505376344
1994	40.36697247706422
1995	37.05357142857142
1996	37.88732394366197
1997	40.625
1998	37.371134020618555
1999	36.81765389082462
2000	29.849137931034488
2001	29.146341463414632
2002	33.04668304668305
2003	30.60428849902534
2004	30.8
2005	29.233680227057707
2006	31.364562118126273
2007	30.098039215686278
2008	37.598944591029024
2009	30.29871977240398
2010	34.430379746835435
2011	31.851851851851855
2012	26.3986013986014
2013	24.72077438570365
2014	24.284253578732105