Year	PPP $ per kg of oil equivalent
1990	2.361185021429612
1991	2.4234949511178683
1992	2.561348557844471
1993	2.65354808850242
1994	2.6409007981115713
1995	2.6789206664430343
1996	2.79692721969066
1997	2.960204157306991
1998	3.233011805507173
1999	3.368925242160358
2000	3.6040132906259785
2001	3.730377631587025
2002	3.7527595835785355
2003	3.6615000208118946
2004	4.208934710377542
2005	4.545007231980559
2006	4.9667014027887575
2007	5.422547592555159
2008	5.664032491358848
2009	5.827822161508824
2010	5.712505753263964
2011	5.932633378051573
2012	5.934207720555677
2013	6.256102059231944
2014	6.43536882582671