Year	% of total fuel combustion
1960	25.6713668249132
1961	25.375754644309488
1962	24.452923548679347
1963	24.09508007991061
1964	25.101985314114767
1965	25.64520691548663
1966	25.72541482917789
1967	27.340849956634866
1968	28.514909643757992
1969	27.760331406808543
1970	26.775453547678996
1971	25.175523349436396
1972	24.887892376681613
1973	24.52175558674636
1974	23.466935551634315
1975	23.09348520627865
1976	22.41180816880595
1977	21.898512095549783
1978	20.091038310545553
1979	20.166610487793132
1980	17.19955125508344
1981	17.817263461711914
1982	17.69411243095454
1983	16.933063184751614
1984	16.682815285636774
1985	16.15633740615339
1986	15.16721029427578
1987	15.304344734409444
1988	15.651848418951197
1989	14.432405766384681
1990	14.04575413996458
1991	14.099496446555479
1992	12.887963318171025
1993	13.489161168708765
1994	13.86515264475923
1995	13.46752842236412
1996	12.747339229500826
1997	13.060554545987458
1998	12.477676838263841
1999	12.319519238273628
2000	12.0924877674374
2001	12.417373118721292
2002	11.837347080095405
2003	11.46432194792019
2004	10.930049187098714
2005	10.396309893627036
2006	10.239798696787036
2007	10.27332885777309
2008	9.800795244281721
2009	8.841330662718802
2010	9.079088106373607
2011	8.77577084473636
2012	8.300874231801265
2013	8.669453462000266
2014	9.59690074539035