Year	% of total energy use
1971	1.6916063867976023
1972	1.6508526457642065
1973	1.5907174556684778
1974	1.509122999490759
1975	1.718927586260674
1976	1.4887569237354723
1977	1.1455419278896777
1978	1.5766229823172828
1979	1.338564302302939
1980	1.5009618188634186
1981	1.2890682799806892
1982	1.375684960458664
1983	2.8532162636758462
1984	5.005635070663426
1985	5.021781997668205
1986	6.1703638621178545
1987	6.8638331946374
1988	6.921197907077888
1989	7.431010800887792
1990	5.112732044787164
1991	4.950546305751458
1992	4.835011052176069
1993	5.94303104955927
1994	6.262026547416452
1995	4.293474364177059
1996	4.996042532859068
1997	4.936209264153709
1998	4.781389501024607
1999	5.833796688531724
2000	5.556711695682816
2001	4.776569157030027
2002	5.413584268081427
2003	5.582074506434803
2004	5.562647860716222
2005	5.4371661386357255
2006	5.435466590553924
2007	5.4811306893727005
2008	8.231988707149254
2009	5.689398309643934
2010	5.467038339368002
2011	6.821406285178673
2012	7.2816123461084565
2013	6.342846857005181
2014	6.213579613985957