Year	% of total fuel combustion
1971	32.14285714285714
1972	30.804516584333097
1973	28.81619937694704
1974	30.15602836879433
1975	30.795664816283374
1976	31.734983243103894
1977	28.731665228645387
1978	28.046458492003048
1979	26.68463611859838
1980	26.409232134931205
1981	26.87465790914067
1982	27.49372440216673
1983	26.676384839650147
1984	26.72931349517097
1985	25.175825485755155
1986	23.94004282655246
1987	25.529694186410605
1988	25.329764863314853
1989	26.37744828848618
1990	24.042124131749944
1991	24.768486523842437
1992	24.84105656420004
1993	24.419376244193757
1994	25.374972017013658
1995	24.124418319862844
1996	25.44047730027035
1997	25.6622936944562
1998	24.360029632068482
1999	22.397103658536587
2000	24.545668181106066
2001	24.325703455314184
2002	24.275866995249828
2003	22.437475702993392
2004	22.416358053999303
2005	22.174431746829086
2006	19.741795082931418
2007	19.958173185620623
2008	22.179699548751927
2009	24.344466668493297
2010	26.89051094890511
2011	28.57402833744963
2012	31.232120964446263
2013	32.57181463316985
2014	30.80658832153575