Year	% of total fuel combustion
1971	25.739264592440215
1972	27.162790697674417
1973	25.572445641716378
1974	25.732788002726654
1975	25.687398911924713
1976	25.53984575835476
1977	26.21225983531565
1978	26.41007859454462
1979	28.447555369828663
1980	28.122527410421615
1981	28.348806366047747
1982	28.50298230175027
1983	29.24766165107767
1984	28.67442733758918
1985	28.250224153389887
1986	26.101820884429582
1987	25.842540476686814
1988	25.335775335775335
1989	25.631569242116914
1990	23.746933052926742
1991	23.561715481171554
1992	27.06081899685001
1993	26.30621138834347
1994	28.943171325442798
1995	29.106675392670155
1996	30.48134729466099
1997	29.934347842586618
1998	30.050001879769912
1999	26.915731278271064
2000	27.63646847770374
2001	26.6951871657754
2002	27.869951888030325
2003	27.292319749216297
2004	27.263771872974722
2005	26.225308272476955
2006	26.977199857499105
2007	27.08368061343557
2008	25.119563209425483
2009	24.86511148139332
2010	24.162905005517104
2011	24.3026554251044
2012	22.146510992229295
2013	22.97489164549395
2014	21.938894783218544