Year	% of energy use
1960	12.335653942186566
1961	12.586700771082118
1962	17.941880543194703
1963	18.02619834503623
1964	19.24357063385389
1965	18.820090522768627
1966	19.350595763955873
1967	16.25670021039854
1968	18.0882742089527
1969	19.435914726701185
1970	23.184991572491263
1971	-23.22800069748862
1972	-16.527791872166127
1973	-17.830343241856447
1974	-12.843718778295804
1975	-13.639669505414657
1976	-15.797469056524431
1977	-15.075676947441357
1978	-15.648313659536655
1979	-21.955139023409583
1980	-18.31978035314126
1981	-9.607241271374948
1982	-12.185262639416075
1983	-13.542205385798411
1984	-15.837422777014307
1985	-17.37592557299604
1986	-16.747501539489107
1987	-15.65849089106175
1988	-16.770075075614027
1989	-18.671150482643043
1990	-23.743672891797388
1991	-19.979038436004767
1992	-19.544082824117353
1993	-17.741736521409504
1994	-18.79053907448249
1995	-18.73451395827265
1996	-18.965106013060733
1997	-19.91234995903395
1998	-22.722458242377847
1999	-22.66105293034184
2000	-24.007833505946074
2001	-24.99571624777604
2002	-24.2487202700134
2003	-22.95563699674066
2004	-22.075361676751744
2005	-20.86636455689046
2006	-18.757574974923525
2007	-17.10868649644932
2008	-16.5003840694513
2009	-14.284517208136004
2010	-12.781346637656966
2011	-10.013243075431582
2012	-8.90517385004234
2013	-7.925181778063457
2014	-6.728703828615618
2015	28.00817540414526