Year	% of total fuel combustion
1971	29.11392405063291
1972	24.671052631578945
1973	20.471464019851116
1974	20.242914979757085
1975	15.973154362416105
1976	18.06451612903226
1977	14.327485380116958
1978	13.571428571428571
1979	13.857142857142858
1980	13.302752293577983
1981	14.110429447852763
1982	17.41472172351885
1983	16.2748643761302
1984	15.708812260536398
1985	17.558886509635975
1986	18.325791855203622
1987	20.042643923240934
1988	21.560574948665298
1989	15.873015873015872
1990	14.917127071823206
1991	14.285714285714285
1992	13.544303797468354
1993	14.338689740420271
1994	14.233128834355826
1995	16.527942925089178
1996	18.244013683010262
1997	18.86160714285714
1998	19.450317124735726
1999	19.712525667351127
2000	19.71399387129724
2001	19.16411824668705
2002	20.762286860581742
2003	20.038910505836576
2004	20.585365853658537
2005	21.498054474708173
2006	18.228279386712096
2007	17.53191489361702
2008	20.927835051546392
2009	26.53333333333333
2010	26.83982683982684
2011	25.17099863201095
2012	22.707423580786028
2013	22.677595628415297
2014	24.267782426778243