Year	kg per kg of oil equivalent energy use
1971	0.85586448850216
1972	0.5913231712173499
1973	0.614949877073049
1974	0.6286777592564358
1975	0.6221666916187439
1976	0.6337754877131063
1977	0.6489984021780804
1978	0.6569344526475697
1979	0.7352400778186048
1980	0.7314740223067108
1981	0.7593864281506594
1982	0.732587405732192
1983	0.7474331816525618
1984	0.7795168369015313
1985	0.7622747468884342
1986	0.7575623334774488
1987	0.7894570608575744
1988	0.816375000718153
1989	0.7690101428127811
1990	0.8453700823059149
1991	0.8090014490727567
1992	0.7495831000857681
1993	0.6988343751499569
1994	0.6811742977387532
1995	0.7074690098118264
1996	0.7327727383704914
1997	0.749879330277222
1998	0.7729342397441741
1999	0.7787483679609091
2000	0.786872418647369
2001	0.8088269807989537
2002	0.8180233381578925
2003	0.8401066269199934
2004	0.8738914139727313
2005	0.9140280213845579
2006	0.9355004057327825
2007	0.9643490236349248
2008	0.9556971862152263
2009	0.955808144378699
2010	0.9675736768175044
2011	0.9600651001907822
2012	0.9651851773281165
2013	0.936994678527451
2014	0.9009916802821198