Year	% of total fuel combustion
1971	11.516547460298218
1972	10.593727555661957
1973	12.757672927164453
1974	12.918002748511226
1975	13.93192488262911
1976	14.328892869136908
1977	15.01075268817204
1978	14.37236001299686
1979	13.658286300667008
1980	13.890932016391721
1981	15.05799723315952
1982	14.28416955017301
1983	15.635557432432432
1984	16.775786197273803
1985	16.28490028490028
1986	16.008294453084503
1987	16.28596855532483
1988	16.39298113915736
1989	15.990065908873822
1990	17.53874018917287
1991	16.237113402061855
1992	15.539082293328333
1993	15.62616474096161
1994	14.586597040905133
1995	14.451359877227384
1996	13.659669924691556
1997	12.759938837920487
1998	12.625591016548462
1999	13.287867910983486
2000	13.953488372093027
2001	14.415463437354447
2002	14.447825014390265
2003	14.188517697423746
2004	13.198662389954274
2005	13.69872180954293
2006	14.378426060109634
2007	14.616174427734494
2008	13.988112086045854
2009	14.448984425889735
2010	15.006907667510937
2011	13.79291312506899
2012	14.278786572552399
2013	15.255268543614136
2014	14.463905202432306