Year	% of total fuel combustion
1971	18.911917098445596
1972	17.528089887640448
1973	20.153061224489797
1974	20.19464720194647
1975	19.81566820276498
1976	21.36752136752137
1977	20.766129032258064
1978	19.928825622775804
1979	18.80597014925373
1980	21.732745961820854
1981	14.017094017094017
1982	13.911620294599016
1983	13.963963963963966
1984	18.282548476454295
1985	15.561959654178676
1986	14.511494252873563
1987	14.502762430939226
1988	16.03905160390516
1989	14.035087719298245
1990	12.522045855379188
1991	13.910761154855644
1992	19.158878504672895
1993	25.757575757575758
1994	31.03448275862069
1995	34.05405405405405
1996	33.33333333333333
1997	34.26573426573427
1998	42.04545454545455
1999	47.94520547945205
2000	47.72727272727273
2001	47.826086956521735
2002	47.2
2003	50
2004	57.356608478803
2005	62.041884816753935
2006	50.65963060686015
2007	55.55555555555556
2008	61.455525606468996
2009	61.00795755968169
2010	56.74300254452926
2011	56.52173913043478
2012	64.65517241379311
2013	67.3076923076923
2014	59.95145631067962