Year	PPP $ per kg of oil equivalent
1990	6.84277918832056
1991	7.137949741458341
1992	7.426328502094835
1993	7.659027542626766
1994	7.99514913235254
1995	8.43987728702935
1996	8.562278098534064
1997	9.284691178680152
1998	9.016656091668539
1999	9.795241943612675
2000	10.26093003643145
2001	10.71205488518297
2002	11.37362454212473
2003	11.804566450092135
2004	12.638283792519156
2005	13.116576796275204
2006	13.728649034874268
2007	15.144653477665418
2008	15.228274876509854
2009	14.94880947215265
2010	15.557498593118225
2011	16.95508741595154
2012	17.52555904784483
2013	17.525696822193076
2014	18.286863188390793