Year	% of total fuel combustion
1971	43.84615384615384
1972	42.10526315789473
1973	39.88095238095239
1974	40.828402366863905
1975	39.583333333333336
1976	44.61538461538462
1977	47.2636815920398
1978	52.97029702970298
1979	55.670103092783506
1980	53.75
1981	54
1982	56.75675675675676
1983	57.04697986577181
1984	57.89473684210527
1985	58.536585365853654
1986	58.02469135802468
1987	52.5
1988	54.06698564593301
1989	58.33333333333333
1990	60.18957345971564
1991	49.81949458483754
1992	50.47318611987382
1993	49.29577464788733
1994	45.47677261613693
1995	46.389496717724285
1996	52.763819095477395
1997	43.737166324435314
1998	43.953934740882914
1999	50.58139534883721
2000	48.74274661508704
2001	46.098003629764065
2002	44.66546112115732
2003	45.346869712351946
2004	47.89207419898819
2005	48.96
2006	45.0920245398773
2007	45.52023121387283
2008	48.045602605863195
2009	50.24630541871922
2010	51.71821305841924
2011	51.74708818635607
2012	45.51495016611297
2013	48.516579406631756
2014	48.12925170068028