Year	PPP $ per kg of oil equivalent
1991	8.543386662709615
1992	8.800671372818211
1993	8.236665562122369
1994	7.941436011662727
1995	7.692545299623954
1996	7.5244535189166415
1997	7.8037004118622955
1998	7.811950084809122
1999	8.217552313316014
2000	9.146827663420389
2001	7.981251067966319
2002	9.174582301820953
2003	9.35763589422092
2004	10.289322511726473
2005	10.038346764578373
2006	11.060215333106914
2007	11.631828955736204
2008	11.427148392261888
2009	11.327472786651875
2010	11.708974643681756
2011	12.164513240409804
2012	12.485253114433474
2013	12.579215915637295
2014	13.271824645560956