Year	% of total energy use
1960	3.8132885307198676
1961	3.6277641962713116
1962	3.292249946286135
1963	3.4291826615769936
1964	3.129877890586743
1965	3.485013074218926
1966	3.7793753288558682
1967	3.494668752838245
1968	3.3598199624251857
1969	3.3389616740819905
1970	2.9829032579282404
1971	2.9147461082300903
1972	3.1726845032350655
1973	3.027569191951917
1974	3.4250967301621897
1975	4.196381833410442
1976	3.82197525970442
1977	5.0496500001963875
1978	5.245916071263941
1979	5.611477523265044
1980	6.305738304543735
1981	8.32897446390481
1982	9.256262622595727
1983	10.561309584284798
1984	12.780796958826652
1985	14.519738517337458
1986	15.385700288181498
1987	15.704968976997666
1988	16.57986593902983
1989	16.67244761109465
1990	16.26564604468826
1991	16.418370253952542
1992	17.17167645703257
1993	17.85593720419445
1994	17.65775247562925
1995	17.526218114637814
1996	17.831309435980852
1997	18.025372889460588
1998	17.565517945262133
1999	17.969429236425764
2000	18.39145009200352
2001	18.35761074167072
2002	18.4103745738192
2003	18.26274205839393
2004	18.324379528297595
2005	17.98564533369083
2006	18.186879211652236
2007	17.85401960073957
2008	18.278017076110842
2009	18.46148251113978
2010	18.743282385577853
2011	19.15904855475267
2012	19.149743035564057
2013	19.76550223200416
2014	20.884999779202932
2015	20.484752527589915