Year	constant 2011 PPP $ per kg of oil equivalent
1990	11.3485724609878
1991	11.6938028317781
1992	11.8976332973206
1993	12.0639093921962
1994	13.2663761657008
1995	13.5575941567348
1996	12.5755384534773
1997	12.9118322964812
1998	13.2980444203604
1999	12.9886518163624
2000	12.5008099462738
2001	12.7311656492853
2002	12.9965657515948
2003	13.0006772681978
2004	13.5276967170267
2005	14.0485122020816
2006	14.9894192303295
2007	15.7007159400595
2008	16.9010969923202
2009	17.6317823392303
2010	17.6859133380279
2011	17.8586330038585
2012	18.1118831419655
2013	21.0077254398136
2014	20.6529091120423