Year	% of total fuel combustion
1971	52.28070175438596
1972	50.73099415204678
1973	49.464922711058264
1974	49.45652173913044
1975	49.953746530989825
1976	52.22465353756382
1977	56.03807257584771
1978	56.304985337243394
1979	55.14950166112956
1980	53.214990138067066
1981	49.41757853865161
1982	47.26647922524212
1983	47.57869249394673
1984	47.408136482939625
1985	42.92007551919446
1986	43.116540112248266
1987	41.065126724414505
1988	43.0453431372549
1989	42.63729631864816
1990	41.91019244476123
1991	46.63827198052936
1992	47.23554657914668
1993	44.44137168141594
1994	42.30895375532962
1995	45.498931949954226
1996	47.04751441911563
1997	52.96108291032149
1998	47.811090474927035
1999	49.78442810043114
2000	50
2001	53.81501720299535
2002	53.95613004308656
2003	53.82053654024052
2004	54.463464016197314
2005	50.797872340425535
2006	47.42125984251969
2007	44.052122740647334
2008	47.78241091736164
2009	53.60237118103056
2010	49.399318630087855
2011	40.75415774740655
2012	40.218078381795195
2013	38.74777544086717
2014	35.38896276595745