Year	% of total fuel combustion
1960	15.330154601936135
1961	14.922048997772828
1962	14.823847058311198
1963	14.983741228820811
1964	14.452644526445264
1965	13.878905170030412
1966	13.978125833619147
1967	13.554724726926178
1968	13.38610254973382
1969	12.38786151504356
1970	12.333459024635495
1971	16.29335567673165
1972	16.434490973448337
1973	16.577054869482502
1974	16.766129681373396
1975	16.406389418618893
1976	16.09840923114489
1977	15.641355036316417
1978	15.39037451492516
1979	15.345276980434853
1980	15.348454705095252
1981	15.6418729212561
1982	15.252907501314162
1983	14.91406586174602
1984	14.515015367796194
1985	14.565997868322142
1986	14.544328286523537
1987	14.342543448299223
1988	14.272349441111771
1989	14.59955822521098
1990	13.59858240688917
1991	13.825912606804195
1992	13.934832116788321
1993	13.892039169567896
1994	13.875935881732085
1995	13.711758657387724
1996	14.64978092150068
1997	14.489838745305942
1998	14.775466074839523
1999	15.169220678027283
2000	15.671353776795732
2001	15.589611181116629
2002	15.563212708358773
2003	15.114214982850976
2004	15.136194249435007
2005	14.696682107632384
2006	14.341963726958172
2007	14.323637398446566
2008	14.716177461460065
2009	14.56773581070927
2010	14.455557803724945
2011	14.29934916032932
2012	14.766029465813034
2013	14.897497600749205
2014	15.039190798767002