Year	% of total energy
1960	1.4875402635990547
1961	1.444659547008994
1962	1.3931425501688868
1963	1.3866403733252588
1964	1.3547478718798223
1965	1.3552849020470343
1966	1.4099262609753316
1967	1.4083369163526087
1968	1.4000448991265833
1969	1.465531240766713
1970	1.1970872421692018
1971	31.04622199856308
1972	30.2346499601822
1973	29.31118272540108
1974	29.047209991553814
1975	27.607501968699257
1976	26.792684004778685
1977	25.39264315273658
1978	23.808868871078797
1979	23.537369176959736
1980	23.666142061899176
1981	24.28413778583796
1982	23.897333429136054
1983	23.538179927833315
1984	23.122031241823297
1985	22.75709130280098
1986	22.28416439298495
1987	21.729982690740457
1988	21.045457865433264
1989	21.021684511750383
1990	11.561318456245832
1991	11.820036793332104
1992	12.156360630850378
1993	12.281876971316656
1994	12.427256586534321
1995	12.02517466175497
1996	11.853356805649746
1997	11.907467594219405
1998	11.850244124936511
1999	11.769255245602526
2000	11.259948967353392
2001	10.610320814407896
2002	10.255382007453782
2003	9.378661417146384
2004	8.540633911807669
2005	7.889285448625974
2006	7.385228680457508
2007	6.798977247988736
2008	6.37257830260886
2009	6.059622822521479
2010	5.475924271310553
2011	4.95410944007621
2012	4.697107617164608
2013	4.431868134182933
2014	4.118068908959888
2015	6.977408148165096