Year	% of total fuel combustion
1960	29.303831227353825
1961	28.667935351300944
1962	27.804382029419642
1963	27.828992142547797
1964	28.454914897086308
1965	28.49392860021915
1966	28.405537225649113
1967	29.40177397163961
1968	28.766279513434462
1969	28.066828421169316
1970	26.037816634743145
1971	27.254151980850928
1972	26.62586010809432
1973	26.494417178888522
1974	26.505322294263056
1975	25.503355704697984
1976	25.298228260819787
1977	25.515799431101126
1978	25.02076151142368
1979	25.43156216620343
1980	25.01638061812609
1981	24.517588819341544
1982	23.856491428070335
1983	23.307309252344997
1984	23.471477969617467
1985	22.79456582288879
1986	22.332416197039805
1987	22.28852293466998
1988	22.15936509303601
1989	21.581121514204654
1990	19.979109712824084
1991	19.433970778471934
1992	18.827834066837546
1993	18.46005711169829
1994	18.480470589174136
1995	19.094870675013343
1996	18.185727243312126
1997	18.092493146569527
1998	17.972937841794984
1999	17.18779246125171
2000	17.365413439218358
2001	17.173063200161995
2002	16.893857937973237
2003	16.918842333203294
2004	17.93983988735409
2005	18.273557222668305
2006	18.636935557256745
2007	19.062297267880478
2008	19.413037570038256
2009	19.525810734668756
2010	19.969064107221644
2011	20.2594641806493
2012	19.78958572964686
2013	19.71794197920333
2014	19.960317638623476