Year	% of total fuel combustion
1971	17.197986577181204
1972	17.10794297352342
1973	16.974494283201405
1974	17.761123007375684
1975	16.763071339457863
1976	16.58717541070482
1977	16.2367526494701
1978	16.15071475906466
1979	15.73873873873874
1980	17.867842876165113
1981	18.99348068055335
1982	20.16488413547237
1983	21.387610619469026
1984	22.681339977851607
1985	23.68438516159002
1986	24.204472843450475
1987	26.70971529204579
1988	26.600212801702416
1989	27.285566842305396
1990	30.891795481569563
1991	31.70019655451497
1992	33.751824817518255
1993	34.27559752139273
1994	34.36835389196087
1995	33.9648536563535
1996	33.93747684591491
1997	33.99863481228669
1998	33.335901782503726
1999	33.780628671139624
2000	34.97860745273323
2001	35.196848590339656
2002	35.21898214879698
2003	33.35156181643189
2004	34.346294199068836
2005	34.94187454589489
2006	35.60397508736992
2007	35.231595435220406
2008	35.040983606557376
2009	36.54792770450532
2010	36.20282590534307
2011	35.426307670733415
2012	34.84937368439215
2013	35.62285951499637
2014	35.57300903639896