Year	% of total fuel combustion
1960	20.095408467501493
1961	19.19561243144424
1962	18.29465731246627
1963	20.25628388368655
1964	17.26618705035971
1965	16.596104995766296
1966	16.440366972477065
1967	17.849898580121703
1968	17.24678582627783
1969	17.50285062713797
1970	18.360914105594958
1971	37.65269661569368
1972	37.25119881962375
1973	36.478489137895856
1974	36.662678627818124
1975	36.95034975454762
1976	37.53268154192181
1977	37.75955171372596
1978	37.736985637630916
1979	36.63724710857795
1980	35.51188073451294
1981	34.56482120962271
1982	34.678686021650044
1983	34.40450177590672
1984	34.58053193068782
1985	32.855119536250434
1986	32.33524794368871
1987	32.235330238270244
1988	31.868311955212242
1989	30.943641784442914
1990	24.04088460717082
1991	23.719517261313385
1992	23.8536365485228
1993	23.13007647366171
1994	23.113717185871913
1995	24.911210015763174
1996	23.347653309605043
1997	23.273245649182886
1998	23.494917904612976
1999	21.990072748728537
2000	21.718160831704846
2001	21.636409754683477
2002	21.486319213696135
2003	21.50180517421687
2004	23.34364293588243
2005	24.304521928608157
2006	24.346650455854675
2007	25.15868641803524
2008	25.46623824772762
2009	25.81031275205772
2010	25.76686509959652
2011	25.710361777975834
2012	24.82519269403696
2013	24.585759315994473
2014	24.757796037455893