Year	% of total fuel combustion
1971	19.36230393417331
1972	19.232558139534884
1973	19.915335770636904
1974	20.62031356509884
1975	22.026172621673282
1976	23.097686375321334
1977	23.89066788655078
1978	24.988441978733242
1979	24.13288758880067
1980	24.121171018424327
1981	23.740053050397876
1982	22.968612496333236
1983	23.65189101260675
1984	23.55989485542621
1985	24.118904752051865
1986	24.563359345968035
1987	24.2304217913974
1988	23.619590286256955
1989	22.62585284897658
1990	22.864820656618765
1991	22.12866108786611
1992	21.390840804458445
1993	23.84943249844356
1994	23.81432049022077
1995	22.783049738219898
1996	23.85635227136999
1997	23.243899662251906
1998	23.95202827173954
1999	23.85324174903669
2000	24.49705279343926
2001	24.53475935828877
2002	25.23691500218691
2003	25.584975369458128
2004	25.130265716137394
2005	25.119118879444514
2006	24.739490559315996
2007	23.02883813968995
2008	23.6458055378805
2009	24.83138935174165
2010	23.416591433443674
2011	23.030100070916397
2012	23.743605763598737
2013	23.52787326259154
2014	24.929417899980216