Year	% of total fuel combustion
1971	28.673323823109843
1972	28.294573643410853
1973	27.450000000000003
1974	26.49746192893401
1975	26.475745178258332
1976	25.768585802124093
1977	25.97750401713979
1978	27.708978328173377
1979	28.12803103782735
1980	29.158878504672902
1981	31.094410521371536
1982	34.05875952121872
1983	32.982640715412934
1984	30.925284512617512
1985	31.49847094801223
1986	31.404549950544013
1987	33.07317073170732
1988	31.209677419354836
1989	27.633333333333333
1990	30.852871219843696
1991	33.54564755838641
1992	35.23972602739725
1993	36.854005167958654
1994	36.275375110326564
1995	36.805180787911496
1996	34.592074592074596
1997	31.829218939700528
1998	33.04712460063898
1999	31.812998859749143
2000	34.93108413906604
2001	34.41920274324903
2002	34.95043239822822
2003	33.60082304526749
2004	31.708231764485284
2005	34.10510841602352
2006	32.84225655767158
2007	31.414525848398352
2008	30.942715381145685
2009	32.248013709300515
2010	31.24362151917189
2011	29.01726427622842
2012	29.04687904687905
2013	29.86221192537495
2014	31.07769423558897