Year	% of total fuel combustion
1971	38.765754019991306
1972	38.125
1973	36.07339449541284
1974	35.82089552238806
1975	33.86316516931583
1976	34.514796971782516
1977	31.695331695331696
1978	31.540270429159317
1979	30.49124788255223
1980	31.383138313831388
1981	32.02655706607651
1982	32.39524702939337
1983	30.80540858318636
1984	32.91652585332883
1985	32.175438596491226
1986	36.56036446469248
1987	31.466176920722372
1988	31.832611832611835
1989	32.622950819672134
1990	36.1198738170347
1991	37.34261987677471
1992	38.887527566772846
1993	38.44055467151625
1994	39.015631601182925
1995	38.679245283018865
1996	40.40875442549083
1997	39.191538684439294
1998	39.25947269845844
1999	40.48896839594514
2000	36.10336220819263
2001	39.24255820807545
2002	40.13167739039354
2003	37.32792348934937
2004	37.8244220677918
2005	35.18466703973139
2006	35.64779490309782
2007	31.84057971014493
2008	31.183249016301296
2009	32.596221133659895
2010	30.787187135261313
2011	30.254695137638283
2012	30.463988058216195
2013	28.51723753207631
2014	27.83408212308014