Year	% of total fuel combustion
1960	29.059829059829063
1961	31.30434782608696
1962	29.032258064516125
1963	29.92125984251969
1964	31.007751937984494
1965	30.000000000000004
1966	29.333333333333332
1967	32.3943661971831
1968	32.21476510067114
1969	37.59398496240601
1970	38.63636363636363
1971	8.34990059642147
1972	7.355516637478108
1973	6.818181818181818
1974	6.236860546601261
1975	5.098980203959208
1976	4.899645808736718
1977	4.375667022411953
1978	4.126337238920021
1979	3.3482142857142856
1980	3.537245110278818
1981	2.3372887450557354
1982	3.1838411502909962
1983	2.6043405676126876
1984	2.6932826362484157
1985	3.086997193638915
1986	2.3940005768676094
1987	2.6263767297373626
1988	2.4331550802139033
1989	2.5607863424728405
1990	3.199681359532661
1991	3.2383767804353676
1992	2.4964131994261116
1993	2.4067746248700046
1994	2.5219941348973607
1995	2.4863910548771524
1996	2.6437913092392074
1997	2.6728487658529936
1998	2.822687516565067
1999	2.1784232365145226
2000	2.355096166426795
2001	2.3857611714213585
2002	2.246922433369188
2003	2.0965763354522133
2004	1.935762950145993
2005	2.003173343911147
2006	1.8912745545911371
2007	1.7381812074901335
2008	1.6782314022914313
2009	1.6623628147191736
2010	1.635704240988824
2011	1.6147389386826005
2012	1.5996773759913965
2013	1.5164225333935601
2014	1.4771322620519158