Year	% of total fuel combustion
1960	13.675213675213676
1961	16.521739130434785
1962	16.12903225806452
1963	17.322834645669293
1964	18.6046511627907
1965	20.000000000000004
1966	21.333333333333336
1967	18.30985915492958
1968	18.120805369127517
1969	15.789473684210526
1970	15.151515151515152
1971	19.28571428571429
1972	20.666666666666668
1973	20.958083832335326
1974	24.096385542168676
1975	19.254658385093165
1976	22.0125786163522
1977	22.699386503067487
1978	25.568181818181817
1979	28.415300546448087
1980	29.714285714285715
1981	24.71264367816092
1982	26.282051282051277
1983	29.559748427672954
1984	34.319526627218934
1985	35.58282208588957
1986	34.705882352941174
1987	30.45977011494253
1988	30.601092896174865
1989	29.67032967032967
1990	28.947368421052634
1991	25.66844919786096
1992	24.736842105263158
1993	24.742268041237114
1994	27.317073170731714
1995	26.53061224489796
1996	28.251121076233183
1997	30.33175355450237
1998	30
1999	28.292682926829272
2000	35.18518518518518
2001	37.61904761904762
2002	37.272727272727266
2003	35.15981735159818
2004	37.44493392070484
2005	37.21973094170403
2006	33.03964757709251
2007	30.17241379310345
2008	28.77358490566038
2009	24.519230769230766
2010	25.128205128205128
2011	25.133689839572188
2012	26.881720430107524
2013	27.093596059113306
2014	29.411764705882355