Year	PPP $ per kg of oil equivalent
1990	6.371148250119261
1991	6.584889496249983
1992	6.769833811121211
1993	6.951146120658383
1994	7.170344843626306
1995	7.269761748684442
1996	7.399035220396918
1997	7.5904306872540195
1998	7.654335160714433
1999	7.683853662303323
2000	8.078000647184346
2001	8.199557570020707
2002	8.309897164015064
2003	8.3867461390281
2004	8.720290345300121
2005	8.992264401354387
2006	9.462108956664217
2007	9.969561240894274
2008	10.342186817108162
2009	10.384836693528733
2010	10.693034692907874
2011	11.207795199051363
2012	11.14728662411805
2013	11.325903066603878
2014	11.413044114245377