Year	PPP $ per kg of oil equivalent
1990	6.360309598805397
1991	6.898886011501936
1992	6.840570524577474
1993	7.352064081474604
1994	7.1685779253385435
1995	7.3964209163196655
1996	7.720568222160542
1997	8.02881965730296
1998	7.805480493680608
1999	8.121914411893668
2000	8.392369746409152
2001	8.439046428957234
2002	8.569609689292216
2003	8.905880148540387
2004	9.216080719787042
2005	10.011901447770475
2006	10.31913884036882
2007	10.950633643862663
2008	11.155609866150781
2009	11.905870013381751
2010	11.05221230521236
2011	11.576611520978231
2012	11.407726306564829
2013	11.418358002459346
2014	11.736843990664374