Year	% of total energy use
1971	4.425587140940027
1972	4.314111550511091
1973	4.5700082910799456
1974	4.007160291491244
1975	4.266127682927645
1976	4.543375522598643
1977	4.467870478659876
1978	4.277169538296955
1979	4.066280076962142
1980	4.310124678924072
1981	4.037213157026506
1982	3.9868845174361676
1983	4.06632348698371
1984	4.056162842024326
1985	4.343614137096495
1986	4.45510219299572
1987	4.267321855413959
1988	4.119945506534725
1989	5.293667280607094
1990	1.4934720630543104
1991	1.6276309299976885
1992	1.7076891236180662
1993	1.900694657939444
1994	1.392090300092101
1995	1.3808621140846553
1996	1.3134656436991747
1997	1.2909827827134663
1998	1.2629083402410783
1999	1.320589869044756
2000	2.8018165670402086
2001	2.7565090157467718
2002	2.573181464249597
2003	2.574083659205475
2004	2.493084577514475
2005	2.5177202732541413
2006	2.837882895483805
2007	2.90919884383247
2008	2.7863157554918927
2009	2.956495377423565
2010	2.684161867033195
2011	2.7103291966025975
2012	2.419477325456038
2013	2.267624710230573
2014	2.3599462771999273