Year	% of total fuel combustion
1971	8.098370927318294
1972	7.468123861566485
1973	7.115441393563627
1974	6.759703445268207
1975	6.2738679759956355
1976	6.215846994535519
1977	5.80568720379147
1978	5.08667594584335
1979	4.814004376367614
1980	4.844209288653733
1981	4.884667571234736
1982	4.787234042553192
1983	4.870848708487085
1984	4.82367758186398
1985	4.499574364587133
1986	4.435629282365669
1987	4.403560830860534
1988	8.235152680932915
1989	8.791474933397916
1990	8.636180769746549
1991	6.412294647588765
1992	7.041212345222695
1993	7.906806090625573
1994	7.544634286811287
1995	7.944634053849072
1996	7.784881534411432
1997	8.343079922027291
1998	11.056711546307628
1999	13.12732342007435
2000	12.87034842379711
2001	12.436153675327558
2002	13.720875500117675
2003	13.738497753049433
2004	14.912663755458516
2005	16.387096774193548
2006	17.040923399790138
2007	15.591292410276525
2008	17.185246239439522
2009	18.891509433962263
2010	17.545045045045047
2011	16.195895143263563
2012	18.537682789651296
2013	18.60701576004067
2014	19.511037265606458