Year	PPP $ per kg of oil equivalent
1990	2.7811983342913162
1991	2.934654953558453
1992	3.1139459098955866
1993	3.2631708166359545
1994	3.478697556083991
1995	3.586503781532793
1996	3.7833915616467997
1997	4.006764835930099
1998	4.103201386405063
1999	4.229524983182668
2000	4.482335268920972
2001	4.64454140732522
2002	4.767268714280737
2003	4.822586524607215
2004	4.97945864056387
2005	5.218458198103449
2006	5.56864493533325
2007	5.933295592913482
2008	6.257326632973727
2009	6.339509866628435
2010	6.441225531762657
2011	6.7071635224115775
2012	6.953272927558283
2013	7.203660526514525
2014	7.348882209666669