Year	PPP $ per kg of oil equivalent
1990	6.812064645702154
1991	7.099515943016763
1992	7.217549136221601
1993	7.7042665288022425
1994	7.768258735022622
1995	7.861036057858492
1996	8.01844988097784
1997	8.135449326665277
1998	7.942853872040105
1999	7.615268754021129
2000	7.833530326105917
2001	8.028488350609651
2002	8.398296882477426
2003	8.449334143071846
2004	8.689116203109648
2005	9.205586406910205
2006	9.843380883718035
2007	10.005825436512449
2008	10.992106360825511
2009	9.681362634131643
2010	9.259712529119243
2011	9.207024927881802
2012	9.891811999794209
2013	9.836591347926738
2014	9.771859299723785