Year	constant 2011 PPP $ per kg of oil equivalent
1990	12.0523420216662
1991	11.9436974416815
1992	12.1191429562649
1993	12.0790150905956
1994	12.4967174117478
1995	11.8426548681702
1996	12.0054382397518
1997	12.0544241279893
1998	11.9155166429814
1999	11.9178370975126
2000	12.129300649034
2001	12.3029075619643
2002	12.2476400018388
2003	11.7058751793508
2004	11.809115309057
2005	11.6977208927549
2006	12.0422595512175
2007	12.2594294816903
2008	12.2925814686472
2009	12.4429988088141
2010	12.3528640302775
2011	12.8508271884927
2012	13.0024930297515
2013	13.2662132326264
2014	14.0592540087655
2015	13.817858621283