Year	% of total energy use
1971	1.0306340328452483
1972	1.176262744271133
1973	1.7094275866018052
1974	2.5225681989969986
1975	3.0690321924081547
1976	2.9082250192850156
1977	1.7764465904102869
1978	1.1215175402756152
1979	1.9791736856563813
1980	2.7186220863939856
1981	2.86361847634048
1982	2.6165893156721243
1983	3.108087888309566
1984	3.9846382364348267
1985	15.339812616406402
1986	43.27548747027077
1987	58.64794131170994
1988	59.041246671378055
1989	66.0753480774191
1990	5.53633018977838
1991	5.847790408717249
1992	6.396788654249496
1993	7.197488632847452
1994	7.55834207047899
1995	7.811590386993268
1996	7.842131403614242
1997	7.689202463285719
1998	8.012998097911737
1999	8.9254114050275
2000	9.959508661469664
2001	9.880036258792666
2002	9.755316764467391
2003	9.359795967462519
2004	9.527156680400001
2005	10.295278300081954
2006	10.829782170569043
2007	11.348136264659308
2008	11.596457991676587
2009	12.3584822242916
2010	12.288515094694786
2011	13.351795248957405
2012	14.149560308207507
2013	15.696475106564712
2014	16.296438010779895