Year	PPP $ per kg of oil equivalent
1990	3.770776228390979
1991	4.001962625352881
1992	4.11273033396541
1993	4.353590741917548
1994	4.439869527072419
1995	4.703771689513387
1996	4.291283412502785
1997	4.4487154474104385
1998	4.741252408360796
1999	4.855622562354162
2000	6.087702585346759
2001	6.165329464566693
2002	6.10774063352783
2003	6.108859511750445
2004	6.27482846851666
2005	6.559317408415915
2006	5.95639997780438
2007	5.963755005548379
2008	6.237739506612231
2009	6.120647686461142
2010	5.954418235567197
2011	6.0899758465028055
2012	6.273229317772067
2013	6.61776238277957
2014	6.869966983698222