Year	% of total fuel combustion
1971	17.130553180709924
1972	17.618068182947308
1973	18.632683544062942
1974	18.24652939532284
1975	18.631681401573523
1976	18.67649927816146
1977	18.993325339451196
1978	21.798795537565404
1979	22.968745308793945
1980	25.415399158900026
1981	25.075417065458378
1982	24.83254703244219
1983	24.77221019921203
1984	24.930035510521733
1985	27.12689831648469
1986	27.63275501379367
1987	28.82970371614109
1988	29.897063979150907
1989	32.158737533674866
1990	34.1090328268751
1991	35.73108739284576
1992	37.56479397772713
1993	38.99052156385867
1994	40.465165329268416
1995	39.83153793261518
1996	44.19919706158708
1997	43.86483149918766
1998	45.395256163883914
1999	46.79524450277146
2000	48.27082267438047
2001	48.48991696914926
2002	49.90562626133009
2003	51.06439508514343
2004	48.30682538213454
2005	48.609205537711254
2006	49.85994071333367
2007	49.903467656301956
2008	48.98358748014614
2009	49.13559747552205
2010	50.384534021195435
2011	51.44400283413199
2012	51.52576200743663
2013	52.13862340437718
2014	51.374007219516166