Year	% of total fuel combustion
1971	12.259161314695884
1972	10.920692798541477
1973	11.065513703649419
1974	9.91481636642927
1975	9.264024704065879
1976	9.179303160087974
1977	12.067741608356151
1978	12.886405959031658
1979	14.07242431741318
1980	11.56327148204189
1981	8.47418912745546
1982	9.605122732123798
1983	11.60149511213341
1984	11.723910171730514
1985	12.351467660093777
1986	13.810552298673247
1987	15.98550552453368
1988	16.03793247186328
1989	17.268028550332264
1990	18.87272884208709
1991	19.16940403566401
1992	19.76141266905979
1993	20.306513409961685
1994	19.723172818381816
1995	20.286162289298314
1996	20.01310615989515
1997	19.406659537960362
1998	18.96486478619044
1999	18.98992036826371
2000	18.00977508049385
2001	18.165499910249505
2002	19.819613063135428
2003	20.170467528906354
2004	19.345995692187195
2005	18.806146313741777
2006	18.499623291357224
2007	18.566788894709273
2008	17.217811246623558
2009	16.942601557986176
2010	15.718954248366012
2011	14.83715740288723
2012	15.220678985519845
2013	15.87787060016079
2014	16.27833254081471