Year	% of total energy use
1960	2.011993197810963
1961	2.0524533126107767
1962	2.1061187863648856
1963	2.0053498650526076
1964	2.0722160676641814
1965	2.1274961338026497
1966	2.138065651227779
1967	2.258473996216603
1968	2.2788708019443953
1969	2.432012624348494
1970	2.4833687575909487
1971	2.823656647107332
1972	3.1445631068769653
1973	3.65104322123249
1974	4.432670634083752
1975	5.370281759302116
1976	5.354750748641143
1977	5.877560476323038
1978	6.418265952682993
1979	6.2530934128642235
1980	6.508258169645867
1981	7.0630979371585445
1982	7.649529699873415
1983	8.143282836453377
1984	8.447388565631107
1985	9.220372630277657
1986	9.910319430537319
1987	9.95025280545627
1988	10.383784036357994
1989	10.524685768156674
1990	10.467012172553854
1991	11.09054375036703
1992	10.781058956727723
1993	10.741833101972412
1994	10.987302448393539
1995	11.317378157291609
1996	11.204198649455153
1997	10.394944879004731
1998	10.568866985143456
1999	11.073446084577327
2000	10.988776423633775
2001	10.934038310865509
2002	11.231011197448224
2003	11.01732181588102
2004	11.198087811369872
2005	11.189510500831783
2006	11.484662162693994
2007	11.439869127412885
2008	11.827899563157377
2009	12.353048065440838
2010	12.108694185044797
2011	12.35589403814904
2012	12.321991310107244
2013	12.595691898408678
2014	12.579032584938837
2015	12.750786429903412