Year	% of total fuel combustion
1971	36.60714285714285
1972	36.43724696356275
1973	39.01734104046243
1974	36.333333333333336
1975	40.36511156186613
1976	38.793103448275865
1977	34.81481481481482
1978	29.242819843342037
1979	40.90177133655394
1980	27.793696275071632
1981	37.264150943396224
1982	34.20195439739413
1983	35.355648535564846
1984	37.65258215962441
1985	34.737827715355806
1986	36.69885864793678
1987	34.307824591573514
1988	26.328903654485053
1989	23.694466095089634
1990	25.181013676588897
1991	23.59796067006555
1992	23.73702422145329
1993	23.117223313686967
1994	22.49221183800623
1995	21.925133689839573
1996	21.44072603516733
1997	20.292123109024516
1998	19.637610186092065
1999	18.27050997782705
2000	23.01176470588235
2001	22.02937249666222
2002	28.24858757062147
2003	23.052064631956913
2004	26.182760855476346
2005	22.710843373493976
2006	20.36410923276983
2007	23.351076139782457
2008	21.8978102189781
2009	18.104133545310013
2010	17.618213660245186
2011	13.219582203795246
2012	18.46414455110107
2013	17.55735677977744
2014	17.78121376111326