Year	% of total fuel combustion
1971	7.541476412247639
1972	7.485612819031725
1973	7.704574495272168
1974	7.60091439571678
1975	7.382027046929284
1976	6.885459573721457
1977	6.751104739665697
1978	6.464805348014155
1979	6.493655990995601
1980	5.700630953693313
1981	6.311748543367696
1982	6.281126003686694
1983	6.204824652726136
1984	6.198647487719453
1985	5.75060336150824
1986	5.852104266183497
1987	5.600703149765137
1988	5.468189494980104
1989	5.179026487168268
1990	5.741761658031088
1991	5.551662993741021
1992	5.2115239157948325
1993	4.932755446877491
1994	5.119513283629109
1995	4.4822899457508765
1996	3.0682326167350755
1997	3.898709606014082
1998	4.032449960987001
1999	4.356811376823444
2000	2.7682225055393848
2001	2.7980668271711973
2002	2.8372712872414088
2003	2.816653153311947
2004	2.757128562027279
2005	2.669551390998823
2006	2.5132505060087613
2007	2.3355153291856934
2008	2.2849380586690087
2009	2.2310318412563492
2010	2.1199943622656816
2011	2.0228020748308273
2012	2.0968231641953814
2013	2.137843707643408
2014	2.1099531954544966