Year	% of total fuel combustion
1971	62.61127596439169
1972	64.81481481481482
1973	64.64891041162227
1974	64.16464891041163
1975	63.74133949191685
1976	63.341067285382834
1977	62.89473684210527
1978	64.73829201101928
1979	64.19753086419753
1980	54.87804878048781
1981	52.36486486486487
1982	54.929577464788736
1983	53.30882352941176
1984	52.18978102189781
1985	54.074074074074076
1986	56.83453237410072
1987	53.50553505535055
1988	52.980132450331126
1989	54.662379421221864
1990	50.390625
1991	49.45054945054945
1992	50.18450184501846
1993	56.118143459915615
1994	42.85714285714286
1995	39
1996	40.74074074074074
1997	46.948356807511736
1998	47.290640394088676
1999	42.073170731707314
2000	40.60606060606061
2001	40.57142857142857
2002	40.43715846994536
2003	40.20618556701031
2004	37.43589743589744
2005	39.15094339622641
2006	34.693877551020414
2007	49.62406015037594
2008	49.00662251655629
2009	47.77070063694268
2010	43.292682926829265
2011	48.98989898989899
2012	55.147058823529406
2013	50.175438596491226
2014	46.70846394984326