Year	% of total fuel combustion
1971	34.51235755512801
1972	35.05717132419226
1973	34.49185268908355
1974	34.58070728291316
1975	35.24214659685864
1976	35.12249787464255
1977	35.32389046270066
1978	35.34874759152216
1979	32.84826974267968
1980	30.769230769230774
1981	30.069241421757194
1982	32.71677628744579
1983	30.89735975379299
1984	31.059517319986124
1985	29.98136924274226
1986	31.848706728477968
1987	30.157084761980702
1988	29.16014409384961
1989	28.999701613044774
1990	27.82103428239396
1991	26.396167323017767
1992	25.99636744879727
1993	24.70300095715331
1994	24.763886665599486
1995	22.431808929298413
1996	21.260407356884144
1997	21.843247041502615
1998	22.380315064285398
1999	21.494520227926017
2000	21.10954395862717
2001	20.889499524408876
2002	21.715513472789336
2003	20.623060331097502
2004	20.410740899790333
2005	22.1154618635217
2006	22.993592159819077
2007	23.523632191173743
2008	23.73809834355028
2009	24.430154379553493
2010	25.87291223723346
2011	26.567880733017176
2012	24.93311103568077
2013	26.42366153548262
2014	25.835399903659177