Year	PPP $ per kg of oil equivalent
1990	8.962252258946714
1991	9.154005453192374
1992	8.545551828568227
1993	8.311991658390754
1994	8.11326833926798
1995	8.254020724909894
1996	8.059180597621205
1997	8.691656730128066
1998	8.486206287112699
1999	8.135559713495546
2000	8.40469932920655
2001	8.270789458730178
2002	7.369986065145956
2003	8.262152992591291
2004	8.606885573433534
2005	9.161533981221432
2006	8.760430831809591
2007	8.868412850606761
2008	8.609136062675377
2009	7.969515438640677
2010	7.612014508241523
2011	8.979803640087448
2012	8.380688247699709
2013	8.756422697693516
2014	8.080818200822984