Year	PPP $ per kg of oil equivalent
1990	2.1424126837773803
1991	1.8064832201221859
1992	1.9154628131526523
1993	2.030096504412235
1994	2.4488976515863357
1995	2.666002005176443
1996	3.295126855174187
1997	3.555533445273065
1998	3.6861552538490034
1999	3.847862856850981
2000	3.72676230279085
2001	3.89369633469455
2002	3.8676539481112617
2003	4.32094508297692
2004	4.766863221912429
2005	4.577539575679429
2006	4.502354121290991
2007	4.866725897601241
2008	5.381539647524033
2009	5.145930895734073
2010	5.231892428717729
2011	5.724312974871331
2012	6.040221879341375
2013	5.756012184796532
2014	6.009244727624215