Year	% of total energy use
1960	2.148620802151409
1961	1.6091561767353866
1962	1.4145259338906175
1963	1.3581200898341104
1964	1.5452000344681547
1965	1.8602805753477307
1966	1.5564734634572228
1967	1.3361370469347817
1968	1.2089519991029403
1969	0.865824937512714
1970	1.1525331851253504
1971	0.5965359356486636
1972	0.8800783025406461
1973	0.8017589361146481
1974	0.9498980625991762
1975	0.6740779232033188
1976	0.7476173757377351
1977	0.8905100144704076
1978	0.8276094071841591
1979	0.8308085459739363
1980	0.8750768005323216
1981	0.8971701115956079
1982	0.8395184709400167
1983	0.822102941861432
1984	0.713925886510061
1985	0.8303549333257606
1986	0.8918695361226685
1987	0.6341520882212687
1988	0.8205151546715708
1989	0.6383634417434899
1990	0.5278347523844579
1991	0.5655702314136696
1992	0.6283819653626849
1993	0.5964950480310036
1994	0.6675818847028465
1995	0.5240225439160949
1996	0.5167194759915605
1997	0.5297725707446491
1998	0.7085770593644128
1999	0.6634635434101591
2000	0.6649023028601191
2001	0.555826476855369
2002	0.7544433033194696
2003	0.6957843129368859
2004	0.8062590152891017
2005	1.096211330570538
2006	1.4291582450442522
2007	1.5220500312705423
2008	1.9003798001628343
2009	2.328621447966632
2010	2.1076482098287657
2011	3.3943671340998938
2012	3.2573760059426498
2013	3.6928305107221426
2014	4.221768053876321
2015	4.800148993867155