Year	PPP $ per kg of oil equivalent
1990	7.003081322416857
1991	7.4742102433683
1992	7.262402238135829
1993	7.385440166706101
1994	7.424055598531192
1995	7.148309725686741
1996	7.507634018507659
1997	7.576618682474083
1998	7.449304108084886
1999	7.411918269453815
2000	7.898863851003779
2001	8.167634770546476
2002	8.216642390043052
2003	8.685661634903846
2004	8.720487223035343
2005	9.021529600091494
2006	10.32603039816788
2007	10.713725489354319
2008	11.40896065586178
2009	11.483421602067128
2010	12.26350448834568
2011	12.370486669265961
2012	12.966092230546636
2013	13.575278009833191
2014	14.127432762285205
2015	13.914316314845882