Year	% of total fuel combustion
1971	26.328895699645624
1972	25.579399141630898
1973	24.011189680627865
1974	25.2246647310936
1975	24.84422724496029
1976	24.85308259429426
1977	24.235477734965613
1978	23.303711931870776
1979	23.99901944762216
1980	22.276194299478124
1981	22.31370465928062
1982	22.41746173381838
1983	20.79303094022229
1984	20.700045055192607
1985	20.637163423087173
1986	19.4207702020202
1987	20.58948208363464
1988	20.206967754327835
1989	20.625956259562596
1990	20.24162595952547
1991	20.740354535974973
1992	19.64763433463273
1993	17.383164110319008
1994	16.149888068428616
1995	16.556409797961738
1996	15.609686923913216
1997	15.515763968915287
1998	15.251735054182392
1999	15.807928171121741
2000	15.162623489115973
2001	15.458045671800317
2002	14.70216606498195
2003	14.41277338793764
2004	13.589046896503051
2005	14.559441168150068
2006	14.481983388496849
2007	15.983680146838775
2008	15.612576103866173
2009	14.170929689859344
2010	14.711515874306574
2011	14.61105653299991
2012	14.27139672720361
2013	13.820344850994502
2014	13.598906752940982