Year	% of total fuel combustion
1960	24.520591009116625
1961	22.610617246748024
1962	22.61961155850308
1963	21.85728341845101
1964	21.7495263015429
1965	21.24406499107026
1966	19.284742303112775
1967	17.937016938003616
1968	16.524070496392383
1969	18.312689539259747
1970	20.06281900274833
1971	18.784145874656367
1972	17.834373643980108
1973	17.615089514066494
1974	17.652123112873962
1975	18.231978991472666
1976	18.720516428039392
1977	17.501199808030716
1978	17.55503910837894
1979	17.112747149927362
1980	18.124564313357855
1981	18.81755268137166
1982	21.071838713793547
1983	18.29506533045795
1984	18.05535217454971
1985	19.00388220812423
1986	20.017280433411948
1987	21.344060577378134
1988	21.74646455310102
1989	19.939065673662828
1990	13.047008670939306
1991	15.30509110860839
1992	16.196620401882157
1993	16.68977725328219
1994	14.67631081364987
1995	14.696619777451186
1996	14.256257517612692
1997	13.661380044975738
1998	11.92695819317636
1999	12.695215769141877
2000	11.157909272940689
2001	12.23026566450764
2002	13.825308663812924
2003	13.478854024556616
2004	13.495031160518781
2005	14.306436378356496
2006	15.185521536066423
2007	14.063417498532003
2008	14.967519554553888
2009	15.892177372337871
2010	16.94193380583913
2011	15.210078490864717
2012	16.045719680366837
2013	15.680635442344562
2014	15.048021788990825