Year	PPP $ per kg of oil equivalent
1990	8.718631676743444
1991	9.227874303320739
1992	9.696734417357428
1993	10.109815039153071
1994	9.881216819343756
1995	9.872430209611126
1996	9.882794496797914
1997	10.25689721181904
1998	7.780809087056877
1999	7.757418655900282
2000	8.017866096316078
2001	8.483926448705951
2002	8.251383161377339
2003	8.232024668131649
2004	9.114627502455134
2005	9.679231310801102
2006	10.147820512572395
2007	10.429954208966329
2008	11.544274859917286
2009	11.375674869291716
2010	11.893624209627465
2011	12.810884110759876
2012	13.116632632211441
2013	14.56906744353089
2014	15.30734423768325
2015	15.59524825107754