Year	% of total fuel combustion
1971	20.916905444126073
1972	23.011363636363637
1973	23.67758186397985
1974	23.135755258126192
1975	21.753794266441822
1976	22.886297376093296
1977	25.092707045735473
1978	25.865800865800864
1979	32.78350515463917
1980	31.15384615384615
1981	31.94915254237288
1982	32.31810490693739
1983	26.239855725879174
1984	20.125223613595708
1985	15.008576329331047
1986	13.350125944584384
1987	12.908777969018933
1988	10.414971521562245
1989	10.399334442595674
1990	12.012012012012011
1991	13.803019410496049
1992	16.396761133603242
1993	13.319088319088317
1994	12.348993288590602
1995	23.60695026962253
1996	21.71875
1997	22.858541360744002
1998	25.392156862745097
1999	23.728813559322035
2000	22.17319360176503
2001	24.740663900414933
2002	24.49494949494949
2003	23.43032159264931
2004	23.412877082395315
2005	24.372909698996654
2006	27.41935483870968
2007	27.443464929091604
2008	24.74187380497132
2009	27.111574556830032
2010	30.234009360374408
2011	26.187576126674784
2012	25.884761626206494
2013	27.209367159185955
2014	26.465272398657376