Year	% of total fuel combustion
1971	69.14186651256861
1972	68.27393431167017
1973	67.34833928081252
1974	66.35932560590095
1975	65.71682991985752
1976	66.33956017971153
1977	65.93676684169367
1978	65.27836355967945
1979	65.4962132389102
1980	65.34085653501064
1981	64.4057137723475
1982	65.77434577434578
1983	65.95955427156417
1984	66.99895489991157
1985	66.39109943598856
1986	67.0575273471315
1987	66.86682569712924
1988	66.50461837627613
1989	65.40311404581396
1990	67.57682102199777
1991	67.8216928352283
1992	66.11435000511405
1993	66.27686824813452
1994	64.61820403176543
1995	63.173026659696816
1996	61.14421930870083
1997	61.95114409400123
1998	62.30717639168343
1999	62.4692118226601
2000	61.349342481417956
2001	62.010786889780114
2002	61.95164326046041
2003	62.1437686091025
2004	62.18615619364682
2005	62.72401433691756
2006	63.24317261204756
2007	62.541488857278324
2008	62.702472293265146
2009	62.89884103591358
2010	62.82227307398932
2011	61.878932523323925
2012	62.38297872340426
2013	60.7937462417318
2014	61.45502645502646