Year	% of total fuel combustion
1971	2.568807339449541
1972	2.5974025974025974
1973	2.6219956300072833
1974	2.698412698412698
1975	3.6605657237936775
1976	4.042179261862918
1977	3.5993740219092327
1978	3.6490683229813667
1979	3.4055727554179565
1980	2.865995352439969
1981	2.7696793002915454
1982	3.0976965845909454
1983	3.2046014790468367
1984	3.5087719298245617
1985	3.6219081272084805
1986	4
1987	3.454085930918281
1988	4.289118347895155
1989	2.951763858891289
1990	2.840158520475562
1991	2.330226364846871
1992	2.8624766645924082
1993	3.1328320802005005
1994	3.0228254164096233
1995	2.95715147857574
1996	2.8968713789107765
1997	2.8776978417266186
1998	2.851108764519535
1999	2.7575442247658692
2000	4.309133489461358
2001	3.944516688339835
2002	3.4010783907092494
2003	2.8368794326241136
2004	2.997076023391813
2005	2.816423481506617
2006	2.8151774785801713
2007	2.558941920644048
2008	3.0321592649310873
2009	3.162598831213475
2010	2.4539877300613497
2011	2.2973835354179966
2012	2.263906856403622
2013	2.729528535980149
2014	2.224281742354031