Year	% of total fuel combustion
1971	37.133550488599354
1972	38.16621499548329
1973	37.48955722639933
1974	37.61634965600971
1975	37.9833206974981
1976	37.50829462508295
1977	40.242952811088614
1978	42.04418344519016
1979	41.39841688654353
1980	43.7569333168988
1981	45.02074688796681
1982	47.0636025998143
1983	44.83241728634552
1984	44.72487001733103
1985	43.05891848264729
1986	41.3355462266914
1987	40.66807044410413
1988	40.6288532675709
1989	40.85263511245385
1990	43.244685582139994
1991	45.23315084009817
1992	41.3757472876227
1993	34.98230900275193
1994	32.498430634023855
1995	33.90790135883241
1996	33.74438790781203
1997	32.170866882777375
1998	38.09586342744583
1999	42.564949045500214
2000	41.92904513553538
2001	42.793029084338755
2002	44.180605918820916
2003	42.86894435593321
2004	43.581652203313425
2005	43.36535822124622
2006	43.17774792925901
2007	44.17677642980936
2008	43.070659176416015
2009	40.754430859634155
2010	40.32049409506322
2011	39.821344616831226
2012	38.87851809304997
2013	37.832958648409296
2014	34.59287029729018