Year	% of total fuel combustion
1960	33.33333333333333
1961	26.086956521739136
1962	33.06451612903226
1963	29.92125984251969
1964	27.906976744186046
1965	25.71428571428572
1966	25.33333333333333
1967	25.352112676056333
1968	28.18791946308725
1969	22.55639097744361
1970	21.969696969696972
1971	20.000000000000004
1972	21.33333333333333
1973	19.760479041916167
1974	22.89156626506024
1975	26.08695652173913
1976	25.78616352201258
1977	28.22085889570553
1978	27.840909090909093
1979	25.683060109289617
1980	29.142857142857142
1981	30.45977011494253
1982	34.61538461538461
1983	35.22012578616353
1984	30.76923076923077
1985	29.447852760736197
1986	31.76470588235294
1987	33.33333333333333
1988	33.87978142076503
1989	34.06593406593407
1990	34.73684210526316
1991	37.4331550802139
1992	39.473684210526315
1993	40.72164948453608
1994	38.53658536585366
1995	39.795918367346935
1996	38.56502242152467
1997	39.81042654028436
1998	37.61904761904761
1999	38.04878048780488
2000	33.79629629629629
2001	31.428571428571427
2002	32.72727272727272
2003	34.70319634703197
2004	31.71806167400881
2005	31.838565022421523
2006	26.87224669603524
2007	26.724137931034488
2008	26.886792452830182
2009	31.73076923076923
2010	30.76923076923077
2011	30.48128342245989
2012	29.03225806451613
2013	32.019704433497544
2014	30.392156862745097