Year	% of total fuel combustion
1971	13.827512473271561
1972	13.980582524271846
1973	13.53846153846154
1974	13.239974538510502
1975	13.443708609271523
1976	12.87188828172435
1977	13.418001104362231
1978	15.1
1979	12.612260835611089
1980	20.24214907302308
1981	25.924542398206952
1982	29.297261629825144
1983	27.89262573279852
1984	22.32304900181488
1985	25.12248230811105
1986	23.538193580492663
1987	21.46499768196569
1988	21.11196025983951
1989	22.304404996712687
1990	10.215827338129497
1991	24.484536082474225
1992	20.542986425339365
1993	16.890459363957596
1994	15.441176470588236
1995	16.512059369202227
1996	17.334605597964376
1997	17.459343356857932
1998	15.036045314109165
1999	14.058479532163743
2000	13.0049686757399
2001	12.206292313819196
2002	12.466487935656836
2003	13.263394529786437
2004	13.411597296335822
2005	12.604263206672847
2006	13.76133155000743
2007	14.179878500518598
2008	14.726840855106888
2009	14.957918898240244
2010	16.279069767441857
2011	14.322533136966126
2012	14.554754708207392
2013	15.279429250891797
2014	15.264869888475838