Year	constant 2011 PPP $ per kg of oil equivalent
1990	13.5950471463084
1991	12.9804835059566
1992	12.6773604595883
1993	13.9456695052703
1994	15.6624295588209
1995	14.4327567861497
1996	13.823115528198
1997	14.768482982681
1998	14.996987110186
1999	13.4731262783669
2000	13.829813454162
2001	15.1633233748765
2002	14.9472431637491
2003	15.1578262539168
2004	13.9965710783412
2005	14.5925060630388
2006	14.1142295342111
2007	15.118877771661
2008	12.3506193786634
2009	12.9465927100101
2010	14.1038974504274
2011	13.7198736307731
2012	13.5344853168209
2013	14.2699065525549
2014	14.385797483703