Year	% of total fuel combustion
1971	4.712041884816754
1972	5.472636815920399
1973	4.807692307692308
1974	7.339449541284402
1975	6.493506493506493
1976	6.382978723404255
1977	5.9760956175298805
1978	5.533596837944665
1979	5.882352941176471
1980	5.936073059360731
1981	4.797047970479705
1982	5.194805194805195
1983	4
1984	4.972375690607735
1985	5.2631578947368425
1986	4.4843049327354265
1987	2.586206896551724
1988	3.3472803347280333
1989	3.0303030303030303
1990	2.755905511811024
1991	3.508771929824562
1992	2.9850746268656714
1993	2.941176470588235
1994	3.741496598639456
1995	2.8037383177570097
1996	2.2792022792022792
1997	0.8333333333333334
1998	22.52747252747253
1999	20.136518771331062
2000	11.445783132530119
2001	17.7007299270073
2002	29.596412556053806
2003	27.613104524180965
2004	11.14864864864865
2005	18.593749999999996
2006	31.354838709677423
2007	31.466030989272937
2008	24.742268041237118
2009	18.7027027027027
2010	29.665071770334933
2011	24.214417744916823
2012	24.353954581049333
2013	26.73992673992674
2014	24.332570556826848