Year	% of total energy use
1960	0.10032600413774624
1961	0.09152557311097634
1962	0.10822547128959868
1963	0.09131650927060656
1964	0.09585412794545127
1965	0.10420342641171146
1966	0.10374633193383094
1967	0.10460337866080073
1968	0.10521830875514429
1969	0.08113787091307721
1970	0.15801012520390476
1971	0.41919667112514136
1972	0.5132900599405701
1973	0.5227198872347637
1974	0.7351191729386661
1975	0.8581265864296571
1976	1.0233443842751908
1977	1.1109431433655996
1978	1.0571005934257984
1979	1.2609344707929804
1980	1.5230928000775754
1981	1.8621736125544535
1982	1.931427876740643
1983	2.275243768606571
1984	2.6149828247423597
1985	3.113774385415118
1986	3.4534554432932376
1987	4.0415286833140724
1988	4.686671463200691
1989	4.84099543527031
1990	6.468178700352697
1991	6.972402255017946
1992	6.905059644004563
1993	6.997355183077325
1994	7.280065302458013
1995	7.496935401826871
1996	7.725453605150517
1997	8.028346257938829
1998	8.630331647447242
1999	8.78912097831043
2000	9.310631481733287
2001	9.75561179663541
2002	10.539693012698049
2003	10.25597010248416
2004	10.553299581710581
2005	10.410529644778501
2006	10.128997230167878
2007	9.804793097880665
2008	10.557214998223358
2009	11.327705644368367
2010	10.316334334833728
2011	10.467129683520028
2012	11.04347906337211
2013	11.532278628108772
2014	12.218330359135315
2015	10.444432936809864