Year	% of total fuel combustion
1971	35.05747126436782
1972	43.10722100656456
1973	42.548596112311024
1974	47.39999999999999
1975	50.09596928982726
1976	44.85981308411215
1977	48.59154929577464
1978	44.082332761578044
1979	46.66666666666666
1980	48.34123222748815
1981	48.49999999999999
1982	41.45077720207254
1983	50.81481481481481
1984	51.12994350282485
1985	53.77207062600321
1986	54.17256011315417
1987	52.22772277227723
1988	50.43050430504306
1989	43.3679354094579
1990	44.189189189189186
1991	47.46423927178154
1992	48.6157253599114
1993	45.03901895206243
1994	46.64778092540133
1995	44.47415329768271
1996	42.678868552412645
1997	42.74252370532458
1998	55.40712468193384
1999	55.721989215098866
2000	52.4070021881838
2001	55.692652832305114
2002	51.1724856696196
2003	53.17884729649436
2004	41.57014157014158
2005	48.15242494226328
2006	48.29637641968632
2007	48.975188781014026
2008	51.17521367521367
2009	49.891186071817195
2010	48.98278560250391
2011	50.000000000000014
2012	49.598796389167504
2013	53.123412899949216
2014	53.634475597092425