Year	% of total fuel combustion
1971	16.18214561358374
1972	16.615776081424936
1973	15.88579795021962
1974	15.173237753882916
1975	14.898053753475441
1976	14.622425629290618
1977	13.518273888154997
1978	13.343861034346629
1979	13.479441427463149
1980	5.376344086021509
1981	5.730027548209361
1982	5.753217259651777
1983	5.822112649345728
1984	5.330646638578491
1985	5.3269654665687005
1986	5.298781666988978
1987	5.08221225710015
1988	5.780559646539029
1989	3.689211850195641
1990	3.2646361480941106
1991	2.6068821689259645
1992	2.0982142857142865
1993	2.3325635103926095
1994	1.5767430401576732
1995	1.4313440077632236
1996	1.4118792599805239
1997	1.3882123721383346
1998	1.2885295603840319
1999	1.1846510430079833
2000	1.1117136659436013
2001	0.9635974304068506
2002	0.7319056654920033
2003	0.8556149732620317
2004	0.9389671361502342
2005	0.9664429530201338
2006	0.8225939128050461
2007	0.784533482768283
2008	0.8469791078486725
2009	0.8588957055214732
2010	0.839120370370369
2011	0.9436834094368343
2012	0.9282970550576201
2013	0.9439899307740711
2014	1.056938288441871