Year	% of total energy use
1971	0.9132384173680486
1972	1.0775960267918168
1973	0.8074177278889594
1974	0.8710079569246975
1975	0.9019173881282504
1976	0.8943147136063596
1977	0.71617802436879
1978	0.15800321351144606
1979	1.1069432185937038
1980	1.3876025777138117
1981	1.3864563034614454
1982	2.208868242869226
1983	2.6292381508359353
1984	2.939478285499518
1985	3.2734307453444584
1986	3.063879114495333
1987	3.1271459234484933
1988	3.340196320865274
1989	4.419682096675853
1990	3.756553057390615
1991	4.059179745948485
1992	3.9867078046900297
1993	3.486124015449308
1994	3.953743243799337
1995	3.57101083629232
1996	3.9299495786792855
1997	3.4222115330280016
1998	2.719765238562127
1999	1.5340862293742759
2000	3.0667786586877637
2001	2.874786678161122
2002	3.2938270372773095
2003	2.3533910112882186
2004	2.1777242508048955
2005	2.2317981895173093
2006	1.941600043988239
2007	2.3596424767410666
2008	2.241563926415679
2009	1.6451120737757043
2010	1.403166666070319
2011	1.4279411020435402
2012	1.5453849704034255
2013	1.4928182842218702
2014	1.4287130347896