Year	% of total fuel combustion
1960	2.4448419797257017
1961	3.4734917733089574
1962	3.8316243928764164
1963	4.7313947757516015
1964	4.586330935251802
1965	4.995766299745977
1966	4.954128440366971
1967	5.713319810682895
1968	5.675760426465973
1969	5.4161915621436725
1970	4.990806409246126
1971	22.827378232660152
1972	21.779192494555204
1973	22.25705329153605
1974	20.967238689547578
1975	21.917109767645133
1976	21.45970252507783
1977	20.406164294109963
1978	17.846270928462708
1979	19.26271403015589
1980	18.660872758430756
1981	17.518663798557508
1982	16.84994892133886
1983	16.8058394160584
1984	16.179169534296857
1985	14.038794971824881
1986	13.534883720930232
1987	13.217382831530742
1988	8.819245643111847
1989	7.945948517866489
1990	7.254993810893351
1991	7.04770935303736
1992	5.977569319089752
1993	6.83896115727756
1994	5.953638702884973
1995	4.19396017909879
1996	3.620237410695296
1997	3.556893247473467
1998	3.134338324902756
1999	3.0705179332779324
2000	2.928135742689867
2001	2.7690539236816716
2002	2.71673454773307
2003	2.7123896575471114
2004	2.7857165290034853
2005	2.6179985929387537
2006	2.5571494121452383
2007	2.926224609504696
2008	2.6203907066949865
2009	2.576573378301087
2010	2.465549876610504
2011	2.318052821493322
2012	2.303344966751404
2013	2.200752063433012
2014	2.259619930036872