Year	% of energy use
1971	21.53846764368568
1972	22.1530126118748
1973	21.38530313065251
1974	21.262588934505235
1975	20.153326317322257
1976	21.124392868201753
1977	21.82725235483484
1978	20.872606894395595
1979	20.488360654261577
1980	20.74525405519164
1981	19.584521888643778
1982	17.975378540607704
1983	16.087859250077326
1984	17.744462832035175
1985	17.97242968441576
1986	18.947175296187744
1987	19.391929848043308
1988	18.695092754211334
1989	18.87641437337302
1990	17.98665747814724
1991	16.94370857589505
1992	16.73113581108892
1993	16.162753097944275
1994	14.974541108817755
1995	15.663967122599162
1996	16.415520230920386
1997	15.646563572078062
1998	16.600576480650545
1999	17.057863612523708
2000	18.354325085805545
2001	16.52602862598823
2002	15.732992127227332
2003	13.058130908451936
2004	14.12630236729793
2005	15.170615874147442
2006	16.499741800177794
2007	16.139159464810454
2008	16.562572134417255
2009	18.704179516189836
2010	19.216395325050758
2011	18.714472913568635
2012	16.98998388367888
2013	18.139649155078256
2014	17.169903312597175