Year	% of total fuel combustion
1960	2.4448419797257017
1961	3.4734917733089574
1962	3.8316243928764164
1963	4.7313947757516015
1964	4.586330935251802
1965	4.995766299745977
1966	4.954128440366971
1967	5.713319810682895
1968	5.675760426465973
1969	5.4161915621436725
1970	4.990806409246126
1971	6.890684348036097
1972	6.775714175317481
1973	6.87448139323858
1974	6.6499092305543925
1975	6.60992812464556
1976	6.2947118382846545
1977	6.19481008998723
1978	5.970149253731344
1979	6.09792061234788
1980	5.622261386971073
1981	5.865478496213822
1982	5.8767027326315935
1983	5.87939210370619
1984	5.9535456049575
1985	5.535291120403096
1986	5.2824897347929305
1987	5.096676532605963
1988	4.921804186087172
1989	4.625564745338163
1990	5.96726842361301
1991	5.807167266026156
1992	5.190747848738051
1993	5.338840760594696
1994	5.086169736001769
1995	4.255065860268389
1996	3.5155729547426753
1997	3.820857732827258
1998	3.6139708289957704
1999	3.782189869222844
2000	3.0437536885534375
2001	3.0458122183427494
2002	2.96678402794836
2003	2.9731752110217355
2004	2.981653351152413
2005	2.899719283266142
2006	2.7956843319535865
2007	2.7122202234324915
2008	2.6750243996316
2009	2.7937382699884776
2010	2.5930238805336105
2011	2.3482059088799416
2012	2.470351716232603
2013	2.4139324012125583
2014	2.4165414362891706