Year	kg per kg of oil equivalent energy use
1971	4.879550532411731
1972	5.123280427209208
1973	5.4198571673181615
1974	4.97003884011688
1975	4.552309938322985
1976	4.966384753600869
1977	4.774333011578853
1978	4.487060273230068
1979	4.024927124792903
1980	4.0058228174924935
1981	3.4038267897033867
1982	2.916569098587736
1983	2.886047966762342
1984	3.0778229820565763
1985	3.0764797920854607
1986	3.2546977073751004
1987	2.9980653357568534
1988	2.925038119411085
1989	2.82742892975572
1990	2.7517572411462647
1991	2.770854783398364
1992	2.5932733284551017
1993	2.597204852577581
1994	2.5848573328790145
1995	2.597386993646403
1996	2.583000120599907
1997	2.5594920739062585
1998	2.5399177678321765
1999	2.543512826896428
2000	2.5678046498548217
2001	2.5348639265380464
2002	2.518165085286393
2003	2.5455827042435364
2004	2.5321271673805614
2005	2.6014086077575316
2006	2.55550078180867
2007	2.5595268548824115
2008	2.5738949161706905
2009	2.5661596115915457
2010	2.5557223608306274
2011	2.598364207073319
2012	2.5748913114733147
2013	2.6276234801482854
2014	2.625030371418302