Year	% of total fuel combustion
1971	16.880093131548314
1972	17.63485477178423
1973	18.56232939035487
1974	18.257956448911223
1975	17.416974169741696
1976	19.38519447929737
1977	17.268623024830703
1978	16.86802973977695
1979	15.684093437152391
1980	15.90335376848179
1981	14.94861413889754
1982	13.422291993720565
1983	14.131994261119083
1984	16.225490196078432
1985	11.388492629576795
1986	11.632825719120135
1987	12.542444821731749
1988	11.952352109832425
1989	13.648293963254593
1990	12.881157154026585
1991	13.781758362273807
1992	14.160902803057882
1993	14.52011291460833
1994	14.963369963369964
1995	14.624005784526393
1996	15.142128279883382
1997	14.255091103965704
1998	15.00608589810468
1999	14.923657855852898
2000	15.156936087168646
2001	15.11111111111111
2002	14.516365771319538
2003	14.841578654808227
2004	15.691888207225633
2005	16.139444803098772
2006	15.0997150997151
2007	16.028285209192696
2008	15.402951191827471
2009	14.26755640292342
2010	13.814346872715882
2011	14.298305748702381
2012	15.171229782235477
2013	15.788549350193188
2014	15.179370373383225