Year	% of total fuel combustion
1971	25.357607282184652
1972	26.49350649350649
1973	27.26153846153846
1974	26.43020594965675
1975	29.95063082830499
1976	29.38951917882226
1977	29.812981298129813
1978	29.155313351498634
1979	29.59874934861907
1980	28.592447278077486
1981	26.977401129943505
1982	25.498575498575498
1983	24.81710748452448
1984	22.70037654653039
1985	25.872576177285318
1986	24.32712215320911
1987	24.36572522738152
1988	22.81279397930385
1989	21.813471502590673
1990	21.316614420062695
1991	24.77064220183486
1992	21.498708010335914
1993	22.977022977022976
1994	20.788704965920154
1995	22.961373390557938
1996	23.022984028048306
1997	22.874015748031496
1998	24.98975829578042
1999	27.07635009310987
2000	28.381962864721487
2001	27.743526510480887
2002	28.369905956112856
2003	27.58343385605147
2004	27.468706536856747
2005	28.197064989517816
2006	26.837972876516776
2007	29.343254610158525
2008	24.715909090909086
2009	22.711594587423722
2010	18.422973959600874
2011	18.340117593848937
2012	17.40909090909091
2013	19.380017841213203
2014	17.51412429378531