Year	% of total fuel combustion
1960	3.733654755787766
1961	3.577786359483465
1962	3.8766137809593744
1963	4.116162038352866
1964	3.753439601413289
1965	4.079504420371061
1966	4.15357982425226
1967	4.096165550821666
1968	4.2103131700649765
1969	4.073435247973915
1970	2.976348736491955
1971	4.038897756868017
1972	4.044275354917782
1973	4.129883455298718
1974	4.029782880527452
1975	4.41559690126449
1976	4.330272870748817
1977	4.4347606837200235
1978	4.476403187773127
1979	4.707788234089852
1980	4.7402891418587965
1981	4.792412371921766
1982	4.793732737800159
1983	4.783559269454061
1984	3.795495972246721
1985	3.822476460122448
1986	3.752634542866716
1987	3.8721083458777077
1988	3.45980746855847
1989	2.862406790136562
1990	4.927414941078462
1991	4.855708794701404
1992	4.224632933831746
1993	4.608310992735796
1994	4.0676179441710945
1995	3.3603593138963106
1996	3.0683632880534795
1997	3.02718533016227
1998	2.8513222018055435
1999	2.7500664909693167
2000	2.6791682820170424
2001	2.5591939068768954
2002	2.4852456321697374
2003	2.3356376207989387
2004	2.3870438641537195
2005	2.4251465202311073
2006	2.347788355852689
2007	2.4574863788371255
2008	2.33604103798384
2009	2.303787840122756
2010	2.2790960112658785
2011	2.1750794110524985
2012	2.158169641426603
2013	2.1315941092270605
2014	2.169859821091956