Year	% of total fuel combustion
1971	20.302661094726776
1972	20.167725648760246
1973	19.62995144390493
1974	19.33766468146544
1975	19.557476890556092
1976	19.19088957029586
1977	19.212124794939623
1978	18.265827762485248
1979	18.331755857976052
1980	17.592130263081103
1981	18.244766191840267
1982	18.131658699659447
1983	18.056456170617807
1984	17.763839020199573
1985	18.84381865604606
1986	18.283643551309506
1987	17.77230243124598
1988	17.70354757204543
1989	17.075514599260384
1990	16.626735751295335
1991	15.695983528592059
1992	14.158884453797246
1993	13.392587301151192
1994	11.926716895936156
1995	11.467596986420144
1996	9.82269853526
1997	10.685551957726615
1998	8.91294844197024
1999	9.465273509526735
2000	8.796730626852588
2001	8.479876342022102
2002	8.046563024652128
2003	7.538378273014003
2004	7.387561188889989
2005	6.792526995961278
2006	6.437727777597732
2007	6.129645981201752
2008	5.764789600522725
2009	5.548304754310673
2010	5.363410416745446
2011	5.1789673240475
2012	5.251868696569942
2013	5.240327835067889
2014	5.255604228474729