Year	PPP $ per kg of oil equivalent
1990	6.5113472724254216
1991	6.741278869747007
1992	6.915072502943039
1993	7.841681338818977
1994	7.154125235100015
1995	7.349837319088068
1996	7.599343642387164
1997	7.543169081327431
1998	7.702364226726566
1999	7.956062744126781
2000	7.924056081015953
2001	8.559987252495638
2002	8.559970423201294
2003	9.098492590521886
2004	10.595921801718305
2005	11.000043179134588
2006	11.957338223850597
2007	12.97080653385861
2008	13.607003284468586
2009	14.08312217631637
2010	14.694730140443447
2011	15.188208985186677
2012	14.674795455729585
2013	16.611052598021992
2014	18.22000616766781