Year	% of total fuel combustion
1960	25.993327267212617
1961	26.645028031867813
1962	28.778304370721436
1963	31.947771921418305
1964	29.621647509578548
1965	28.896512292738706
1966	28.236083165660634
1967	27.125550660792953
1968	27.49623682890115
1969	28.00292077400511
1970	26.18481534316056
1971	24.3594766120818
1972	25.04212299915754
1973	23.990834961924662
1974	21.514740523948888
1975	24.71382002880752
1976	25.648681310869414
1977	24.460171878385214
1978	23.908785674314494
1979	23.09601567602874
1980	23.170060539350576
1981	21.337801982963274
1982	20.5086379476533
1983	20.80042934907613
1984	19.998521366257577
1985	21.55402963498374
1986	19.574287532706318
1987	17.753922378199835
1988	22.088073138390676
1989	21.19431538671768
1990	20.027614773904038
1991	23.261469698961484
1992	20.957806186659603
1993	21.10790906179955
1994	20.440291821323438
1995	19.445973215923683
1996	21.42568309167581
1997	19.008264462809915
1998	18.099193451306128
1999	17.65144918522204
2000	17.54907424608335
2001	18.14358666266146
2002	17.35428160230271
2003	17.65329563527125
2004	17.42857142857143
2005	16.9331177773786
2006	17.509679798414354
2007	15.620795107033638
2008	17.371720737719887
2009	17.909979939819458
2010	19.428100729583427
2011	16.394583649708935
2012	18.033837477569854
2013	18.867197534035448
2014	15.053256033436698