Year	PPP $ per kg of oil equivalent
1990	2.60680826440836
1991	2.500315960931791
1992	2.1038408742491375
1993	2.3677339615013606
1994	2.7314710914722244
1995	2.98114620545056
1996	3.1559511624138303
1997	3.5612395701928996
1998	3.9351020785112296
1999	4.4508444284609645
2000	4.967999821935228
2001	5.142911496107981
2002	5.717367734605303
2003	5.852848597582357
2004	6.261275007372281
2005	6.87931233620391
2006	7.503068013223949
2007	8.3679947677792
2008	9.29243962627009
2009	8.280520078572561
2010	8.239538473355589
2011	9.313901142580667
2012	9.808643053516002
2013	10.499748593265949
2014	10.940433120970912