Year	constant 2021 PPP $ per kg of oil equivalent
1990	13.417833815766592
1991	12.53280116419091
1992	12.463987837324174
1993	12.158892465280841
1994	12.500857444568588
1995	12.43648327981988
1996	13.370737836201506
1997	13.191688928389157
1998	13.396634723352676
1999	12.9513264172617
2000	13.234468875631697
2001	13.603800600992438
2002	13.404624531802009
2003	13.432956436790908
2004	13.865159037706906
2005	14.033626285806255
2006	13.485562274270904
2007	13.10216615042374
2008	13.273054158595567
2009	12.282195262354687
2010	13.08903893570395
2011	12.923674666459299
2012	12.039693502021564
2013	11.933600855588445
2014	11.438870195936918