Year	PPP $ per kg of oil equivalent
1990	5.709792513897854
1991	5.885602978124676
1992	5.781849629388839
1993	6.05256821962194
1994	6.02104013145325
1995	6.139335132909076
1996	6.39937811002971
1997	6.50630823073376
1998	6.362613547301648
1999	6.496445878100131
2000	6.701265396233561
2001	7.374377772487582
2002	7.6625417324076786
2003	8.190381623078537
2004	8.991880667845134
2005	9.71608709462471
2006	10.625926062477772
2007	11.602015895340555
2008	11.890651878495726
2009	12.747030719585291
2010	13.090461666379975
2011	13.784027101428906
2012	14.113984334599817
2013	14.522136697152257
2014	14.558950915619858