Year	% of total fuel combustion
1971	26.46675358539765
1972	25.83333333333333
1973	29.394495412844034
1974	30.38652889399158
1975	30.131306150656524
1976	30.075705437026844
1977	34.244471744471745
1978	31.834215167548496
1979	34.076792772444946
1980	33.15331533153315
1981	33.03825482137212
1982	33.39587242026266
1983	34.773662551440324
1984	33.42345386955052
1985	36.35087719298246
1986	30.18223234624146
1987	36.76155494337313
1988	34.891774891774894
1989	35.54644808743169
1990	27.996845425867512
1991	32.14572729708009
1992	31.560891938250425
1993	29.46124119117981
1994	32.02365863962822
1995	30.81761006289308
1996	32.07273897650467
1997	32.35294117647059
1998	34.10171445036738
1999	31.64877757901014
2000	37.45411833798267
2001	37.2236958443855
2002	36.91455932964238
2003	38.96536733806695
2004	39.28520777194724
2005	42.99104644655848
2006	40.47001373416755
2007	42
2008	44.47723440134907
2009	43.8628411476557
2010	45.169238749837895
2011	46.12811937226653
2012	47.92884687150143
2013	49.737811000780994
2014	50.16194754989031