Year	% of total fuel combustion
1971	4.10958904109589
1972	5.194805194805195
1973	5
1974	5
1975	3.9215686274509802
1976	5.376344086021505
1977	4.511278195488721
1978	4.195804195804196
1979	3.896103896103896
1980	4.1916167664670665
1981	4.571428571428571
1982	4.787234042553192
1983	3.431372549019608
1984	2.8037383177570088
1985	1.6806722689075633
1986	1.7391304347826086
1987	2.192982456140351
1988	1.6064257028112447
1989	1.4705882352941175
1990	1.5151515151515151
1991	1.6460905349794237
1992	1.3215859030837003
1993	1.2396694214876034
1994	1.1764705882352942
1995	1.2195121951219512
1996	1.2295081967213115
1997	1.1673151750972763
1998	1.8656716417910446
1999	1.6666666666666667
2000	1.4336917562724014
2001	2.214022140221402
2002	3.103448275862069
2003	4.026845637583892
2004	3.98671096345515
2005	5.460750853242321
2006	19.29260450160772
2007	32.28155339805826
2008	33.02107728337237
2009	32.432432432432435
2010	32.475247524752476
2011	30.37475345167653
2012	31.08614232209738
2013	33.84615384615385
2014	32.615894039735096