Year	% of total fuel combustion
1960	32.91592128801431
1961	33.94271785496649
1962	33.027522935779814
1963	31.789058649581076
1964	32.05935251798561
1965	33.19220999153259
1966	32.80733944954128
1967	30.493576741041245
1968	29.570398243963623
1969	26.68187001140251
1970	26.976622012083006
1971	25.763986267588606
1972	25.61692660446321
1973	25.195779799108315
1974	25.02797943882654
1975	25.18367536017047
1976	24.57833817407717
1977	24.948430072809398
1978	26.1701958286897
1979	25.315905743740796
1980	24.645552607092398
1981	24.691205854114227
1982	23.672832462638237
1983	23.6321324627865
1984	23.66283084004603
1985	23.32234937881284
1986	22.771553299929035
1987	22.6054160750073
1988	22.607905142203602
1989	22.420714385507374
1990	21.738031611874135
1991	21.798047154084305
1992	21.797136553681906
1993	22.18998303722882
1994	22.181229063717044
1995	21.838703570993953
1996	22.15897723825934
1997	21.600385501935182
1998	21.31153859838467
1999	21.271983346493432
2000	21.164521442078936
2001	20.927136221237983
2002	20.895643565393666
2003	20.81471568872054
2004	20.751466162098787
2005	20.75030031195904
2006	20.45031896868604
2007	20.709015604324478
2008	20.946743002744636
2009	21.072130163350142
2010	21.086304601681608
2011	21.24566698222662
2012	21.571840620772395
2013	21.60279859061362
2014	21.3688897385043