Year	% of total fuel combustion
1971	33.35079905685093
1972	34.96681980602347
1973	35.199999999999996
1974	34.491315136476416
1975	34.375
1976	34.36261214270811
1977	34.910767996791655
1978	35.95727848101266
1979	34.74370922646784
1980	36.357117246324854
1981	35.87110481586402
1982	35.114503816793885
1983	33.55033343918704
1984	32.52181901699586
1985	34.62130541871921
1986	34.08660154541479
1987	32.42483843776342
1988	33.00161377084454
1989	35.025585779692975
1990	31.33837261004891
1991	31.012087317337183
1992	31.992525570416998
1993	31.916456759026033
1994	32.4163179916318
1995	33.15207021560771
1996	33.556507766470276
1997	32.80881857960283
1998	32.36631644974126
1999	30.57575757575757
2000	30.38118988243676
2001	29.59941636821859
2002	30.059993684875273
2003	29.237058858894965
2004	30.97798259088582
2005	31.021841276398003
2006	30.68606251228622
2007	30.954349223844954
2008	30.464426439987598
2009	32.4325500435161
2010	32.0145539709757
2011	33.52768473721209
2012	34.26216800620129
2013	35.269709543568474
2014	35.61581578548705