Year	PPP $ per kg of oil equivalent
1990	3.012332476353061
1991	3.011488770777561
1992	3.0793736662787237
1993	3.0219919500597845
1994	3.073841381471031
1995	3.1228616841512595
1996	3.2443770226258426
1997	3.352867822983116
1998	3.429854859165377
1999	3.4392080890209846
2000	3.622444020545604
2001	3.7204612817839027
2002	3.952631683041287
2003	4.011485257411616
2004	4.219097293259398
2005	4.510848427709485
2006	4.848483462975664
2007	5.076279068509448
2008	5.125023862731083
2009	5.27357061394767
2010	5.48574429681033
2011	5.6742311610174605
2012	5.696970791518957
2013	5.969495796225963
2014	6.29648316153232