Year	constant 2011 PPP $ per kg of oil equivalent
1990	12.8867342564494
1991	13.1477663313011
1992	12.1520516523989
1993	11.623105907746
1994	12.0023601109324
1995	11.4592813537737
1996	12.252603253103
1997	11.7010494502001
1998	12.311930270221
1999	11.7052816097231
2000	11.8673465273433
2001	12.0142542503302
2002	12.1889812144027
2003	12.9726217311158
2004	11.4591576555308
2005	11.1821450661006
2006	11.8289067354872
2007	11.8740511367264
2008	12.1130002037234
2009	12.5366564601439
2010	12.4068933346826
2011	12.1184611485894
2012	12.3093420063527
2013	12.81317935397
2014	12.9905236342359