Year	% of total fuel combustion
1971	31.385905161121297
1972	29.91322103113833
1973	30.690909090909084
1974	33.99503722084367
1975	32.97872340425531
1976	33.59065303567703
1977	31.401644275115302
1978	29.272151898734176
1979	31.425908667287977
1980	28.433130154177128
1981	27.372521246458923
1982	25.937234944868532
1983	24.420450936805334
1984	23.08987903843209
1985	22.860221674876854
1986	22.21898235894445
1987	20.82045518404046
1988	19.419042495965577
1989	16.01131160786426
1990	18.666073810582482
1991	17.553671297131515
1992	14.899685287175451
1993	14.819479429051217
1994	16.30753138075314
1995	14.911276473955349
1996	14.39921442599536
1997	14.725681588690676
1998	14.37196173749412
1999	15.075757575757576
2000	15.618097613110079
2001	15.0616792678074
2002	14.606883485948847
2003	15.811940119040461
2004	13.47215110655971
2005	13.605617803480145
2006	13.63770395124828
2007	14.126940387618262
2008	14.207287377695135
2009	14.125326370757179
2010	15.511689180711805
2011	15.48608526650953
2012	16.27432581290033
2013	16.036356451294207
2014	15.872595061354339