Year	constant 2011 PPP $ per kg of oil equivalent
1990	12.6886890372679
1991	11.5742503767169
1992	11.2764301223604
1993	11.7496951569535
1994	13.0617102502403
1995	11.3898240283861
1996	11.6402701209527
1997	11.1049358213978
1998	11.0896820440145
1999	11.2082935207362
2000	11.4666452402844
2001	12.724541234589
2002	13.5257850010849
2003	11.9874261242825
2004	13.1401694371032
2005	13.6597539858002
2006	10.0359295502429
2007	9.81562381924111
2008	8.76821286112714
2009	10.0284963999677
2010	9.66191676881142
2011	8.38662020466465
2012	8.55783725828955
2013	10.5451669171657
2014	8.81445970025452