Year	% of total fuel combustion
1971	15.772113943028485
1972	15.810850014505368
1973	14.997391757955139
1974	15.001258494840172
1975	15.795586527293846
1976	15.079707022834985
1977	15.094715852442674
1978	15.180679135645542
1979	15.170008718395815
1980	14.041627834731282
1981	13.41991341991342
1982	13.238208481965914
1983	14.296665389037944
1984	15.106732348111658
1985	14.650647381313423
1986	15.60687066317825
1987	13.935666028032669
1988	13.674311486421649
1989	13.894200127469729
1990	6.747041750390712
1991	6.244151424925562
1992	6.108296653101901
1993	5.898530498317052
1994	6.050355399503297
1995	19.46602995441719
1996	20.113859935535185
1997	21.57956428600299
1998	21.294881588999232
1999	21.954236239950525
2000	21.192719948205166
2001	21.07748819310828
2002	21.223513328776484
2003	20.056390331121275
2004	18.794220229197812
2005	18.9953944534641
2006	18.768423439473942
2007	18.289696741382556
2008	19.44840252050284
2009	17.65853335978311
2010	17.039581393855734
2011	18.24129012627415
2012	18.749065686010706
2013	16.50927435479406
2014	16.55437334227615