Year	% of total energy use
1971	0.9176100058490902
1972	1.4340714937885546
1973	1.3568410236015274
1974	1.5165738101491082
1975	1.5540961442529615
1976	1.246931907089603
1977	1.3504227248081562
1978	1.4234360228972591
1979	1.5315231609515794
1980	1.666148810004638
1981	1.691634541323455
1982	1.573926016318781
1983	1.3222292186545659
1984	1.5048453069247996
1985	1.6835993970987069
1986	1.3941168855273416
1987	1.3873943133951527
1988	1.8166431535722911
1989	1.7002443735960306
1990	1.329431880086626
1991	1.9626961047096183
1992	1.643104593529935
1993	1.582332130213537
1994	1.6176068273554456
1995	1.8900201207597576
1996	2.595465186768805
1997	5.39149506091323
1998	6.076055976694457
1999	6.658021229902203
2000	6.235893780948552
2001	6.217639156860979
2002	6.163831746987127
2003	5.241399752432167
2004	6.290348950210946
2005	6.741522168572189
2006	6.298315418269786
2007	7.394872658832141
2008	9.85024123309085
2009	11.34792603627085
2010	12.097029306861295
2011	11.312588316217695
2012	11.300844340917884
2013	13.378114071334704
2014	14.515462493970208