Year	% of total fuel combustion
1971	43.34454589139837
1972	39.74295600593178
1973	36.63594470046083
1974	40.46709129511677
1975	35.8974358974359
1976	36.331078392359736
1977	38.41951930080117
1978	39.1919191919192
1979	35.107816711590296
1980	34.580052493438316
1981	36.58215344089562
1982	34.6443788921665
1983	40.46399517927087
1984	40.31186832226393
1985	34.81504507304942
1986	31.96946564885496
1987	33.33333333333333
1988	31.963845521774857
1989	32.72390037095919
1990	31.583577712609966
1991	27.683615819209038
1992	28.497409326424872
1993	28.98624554253694
1994	28.2876064333018
1995	29.500891265597147
1996	29.918032786885245
1997	35.392194012883664
1998	37.888675623800374
1999	41.65117143919672
2000	40.12435991221653
2001	44.293272864701436
2002	31.022187004754358
2003	23.06122448979592
2004	20.478943022295624
2005	25.189620758483034
2006	30.345911949685533
2007	30.93880653743824
2008	27.875932469572046
2009	34.60620525059666
2010	34.27172582619339
2011	32.280819617064154
2012	31.553079947575362
2013	30.04758667573079
2014	29.88115449915111