Year	% of total fuel combustion
1971	15.56122448979592
1972	14.678583705740804
1973	14.972393634296852
1974	15.133248730964468
1975	16.04489930670188
1976	16.14867029798142
1977	17.141941685357256
1978	17.757296466973887
1979	18.2356423919479
1980	17.47231974075074
1981	18.196994991652755
1982	20.066982975160478
1983	20.4403370481109
1984	21.035422343324253
1985	23.492303810244763
1986	23.97575757575758
1987	25.581965204606714
1988	25.52655677655678
1989	24.603534209333933
1990	23.405639913232108
1991	25.374119718309856
1992	26.275016139444805
1993	28.816503800217152
1994	28.21184051550544
1995	27.19298245614035
1996	26.784242624031645
1997	27.14719271623672
1998	27.043090638930163
1999	28.40643475869654
2000	28.31317466510599
2001	28.22715342400382
2002	28.484024473147517
2003	26.74120422607447
2004	28.636188271604937
2005	29.400440044004405
2006	30.547476475620186
2007	30.27303209324605
2008	30.601010481864115
2009	30.00769069425994
2010	29.380230125523006
2011	28.6509040333797
2012	29.35703703703704
2013	29.516415979298074
2014	29.864729458917832