Year	constant 2011 PPP $ per kg of oil equivalent
1990	15.0505381483455
1991	11.5343729120247
1992	13.3810015662885
1993	13.0518076994435
1994	13.3193423919463
1995	13.8445199642758
1996	13.8779869849575
1997	13.6819613994198
1998	13.9442641154587
1999	13.4373350459565
2000	13.1741839074326
2001	13.5697076204046
2002	12.7631915810397
2003	11.6595523487015
2004	11.533695140196
2005	10.5107455709567
2006	7.10972989429417
2007	6.47494336934158
2008	7.92075143914073
2009	8.31814733816192
2010	7.36638410186958
2011	6.19419974439804
2012	6.29756052423749
2013	6.36819928863066
2014	6.57225071133839