Year	PPP $ per kg of oil equivalent
1990	7.555946315618411
1991	7.596381936015327
1992	7.106423711187865
1993	7.011157472889251
1994	7.0449930103436245
1995	7.734274402109946
1996	7.553646371642514
1997	8.257162703230433
1998	8.728124714644526
1999	7.5107619464522895
2000	7.925726178566515
2001	8.245185401237071
2002	7.619939648183427
2003	7.831071217761195
2004	5.887915987605249
2005	5.929347431262529
2006	6.390513356842534
2007	6.16540254794837
2008	6.5513552371118795
2009	7.452281132064416
2010	7.436126479993593
2011	6.264468438724585
2012	6.11306118132827
2013	6.403587317571434
2014	7.202214884903799