Year	PPP $ per kg of oil equivalent
1990	4.225964869770383
1991	4.6125981902647135
1992	4.923297669887296
1993	5.313966347054601
1994	5.389683825066208
1995	5.69871629763486
1996	5.726109327687817
1997	5.586393060591277
1998	5.683889163549325
1999	5.4101132091153366
2000	5.775474474017879
2001	6.207873876814088
2002	6.28510577479391
2003	6.642819315727135
2004	6.832555763052762
2005	7.233993135379405
2006	8.673441917307734
2007	9.090572435797393
2008	9.092124048004571
2009	9.190513054007473
2010	9.979882082074365
2011	10.388339810819202
2012	10.060340272891514
2013	10.147968348656699
2014	11.159858559003421
2015	11.251860817097606