Year	% of total fuel combustion
1971	29.117772922813575
1972	29.00621911739649
1973	28.83302716813304
1974	27.421731123388575
1975	25.55043616033218
1976	25.034521556794356
1977	26.0144868560267
1978	26.383811810770716
1979	26.692762675032736
1980	27.775700416857088
1981	27.774027798823578
1982	28.206951242855975
1983	28.536280233527936
1984	29.08360525377718
1985	28.61026902842539
1986	30.888025839185072
1987	29.674658182782263
1988	30.74613217339727
1989	30.842157985117346
1990	30.149672365016805
1991	30.55911124681456
1992	30.981037418879733
1993	30.58693145563031
1994	30.792876828492684
1995	30.555411984825145
1996	30.480321316385776
1997	31.65969953085923
1998	33.19933645212537
1999	32.8851386685339
2000	33.75080829050812
2001	34.10764680457979
2002	33.91163720111089
2003	34.90383256138833
2004	34.12801366829083
2005	34.42340528165509
2006	34.22959686818276
2007	34.50470233021771
2008	34.319114452222486
2009	35.42888149735032
2010	34.09480108170296
2011	33.56773260485296
2012	34.86576310554862
2013	35.327842772529245
2014	35.501839707573815