Year	% of total fuel combustion
1971	8.21917808219178
1972	3.896103896103896
1973	5
1974	7.5
1975	12.745098039215685
1976	12.903225806451612
1977	12.030075187969924
1978	11.88811188811189
1979	14.285714285714285
1980	14.970059880239523
1981	15.42857142857143
1982	14.893617021276597
1983	13.725490196078432
1984	14.485981308411214
1985	15.96638655462185
1986	16.956521739130437
1987	17.10526315789474
1988	16.867469879518072
1989	24.632352941176467
1990	26.136363636363637
1991	27.983539094650205
1992	23.348017621145374
1993	22.72727272727273
1994	24.31372549019608
1995	23.17073170731707
1996	21.721311475409838
1997	21.789883268482495
1998	22.761194029850746
1999	22.916666666666668
2000	25.089605734767023
2001	22.14022140221402
2002	18.275862068965516
2003	19.127516778523486
2004	17.940199335548176
2005	16.38225255972696
2006	12.861736334405146
2007	9.223300970873787
2008	8.430913348946136
2009	7.484407484407485
2010	7.128712871287128
2011	7.297830374753452
2012	7.116104868913858
2013	6.666666666666668
2014	6.622516556291391