Year	% of total fuel combustion
1971	25.247524752475247
1972	22.299168975069254
1973	22.044334975369463
1974	20.56737588652482
1975	22.03791469194313
1976	22.368421052631582
1977	24.066797642436153
1978	22.04255319148936
1979	23.36227308602999
1980	22.60869565217391
1981	22.54249815225425
1982	23.357142857142858
1983	22.501654533421576
1984	23.199490121096243
1985	20.542168674698793
1986	20.630202140309155
1987	20.77771329077191
1988	17.766497461928935
1989	19.307400379506646
1990	14.053867403314918
1991	16.185160866710437
1992	15.159235668789808
1993	13.056708160442602
1994	13.540569020021072
1995	15.011977641735427
1996	13.243313425084393
1997	13.259958071278827
1998	13.714902807775378
1999	13.597883597883598
2000	12.393162393162394
2001	12.654614652711704
2002	12.80871670702179
2003	13.885250196489388
2004	13.654719838465423
2005	14.764923402007396
2006	15.177638453500522
2007	15.246067985794012
2008	15.578144853875475
2009	16.612943218447807
2010	15.876242095754293
2011	16.15318784766795
2012	15.992167101827675
2013	15.376297577854672
2014	15.180935569285085