Year	% of total fuel combustion
1971	19.724770642201833
1972	22.07792207792208
1973	28.987618353969413
1974	27.539682539682538
1975	36.93843594009983
1976	30.228471001757477
1977	31.064162754303595
1978	29.7360248447205
1979	29.721362229102162
1980	32.687838884585595
1981	30.976676384839656
1982	26.76727561556791
1983	26.29416598192276
1984	25.64745196324144
1985	21.201413427561835
1986	19.999999999999996
1987	19.966301600673965
1988	24.70214455917395
1989	32.97336213102952
1990	35.99735799207397
1991	34.021304926764316
1992	25.94897324206596
1993	18.734335839598998
1994	24.61443553362122
1995	17.80325890162945
1996	19.640787949015067
1997	19.037078029883784
1998	18.84899683210137
1999	19.77107180020812
2000	22.201405152224822
2001	23.62375379280451
2002	20.323517212774785
2003	17.54385964912281
2004	20.57748538011696
2005	22.259925347811336
2006	23.592411260709916
2007	29.72972972972973
2008	28.269525267993874
2009	20.900653145410793
2010	19.66419115272845
2011	18.219527760051054
2012	20.860284605433378
2013	21.867245657568237
2014	24.189063948100088