Year	constant 2021 PPP $ per kg of oil equivalent
1990	14.08607739335496
1991	12.848907093368746
1992	12.518288292651642
1993	13.043673372644271
1994	14.500178933700074
1995	12.644170117915227
1996	12.922197503754228
1997	12.327907553649823
1998	12.310973898160976
1999	12.442647898204319
2000	12.729451547152825
2001	14.12587794522473
2002	15.015361616284485
2003	13.307585333506294
2004	14.587278725894844
2005	15.164084426140253
2006	11.141173051350819
2007	10.896605344791343
2008	9.733844418480691
2009	11.1329212981756
2010	10.72597074243819
2011	9.310227473035868
2012	9.50030043182136
2013	11.706492048529718
2014	9.769291035691435