Year	% of total fuel combustion
1971	13.93188854489164
1972	14.497041420118345
1973	14.689265536723164
1974	14.488636363636365
1975	14.739884393063585
1976	18.387909319899244
1977	14.18269230769231
1978	13.734939759036143
1979	12.195121951219514
1980	15.034168564920275
1981	11.888111888111888
1982	11.302211302211303
1983	7.466666666666668
1984	6.950672645739911
1985	5.228758169934641
1986	10.9404990403071
1987	10.516605166051662
1988	9.29368029739777
1989	9.15492957746479
1990	7.608695652173915
1991	7.721280602636536
1992	8.426966292134832
1993	9.09090909090909
1994	10.43643263757116
1995	8.551483420593367
1996	9.14927768860353
1997	10.11608623548922
1998	17.021276595744684
1999	20.579710144927535
2000	28.221649484536083
2001	22.316384180790962
2002	16.544655929721817
2003	15.870307167235492
2004	21.428571428571427
2005	22.86096256684492
2006	22.511848341232227
2007	22.434367541766107
2008	27.2108843537415
2009	28.283796740172583
2010	20.33898305084746
2011	22.526501766784452
2012	19.32367149758454
2013	21.880341880341884
2014	13.360323886639677