Year	PPP $ per kg of oil equivalent
1990	3.714303992930936
1991	3.8328772948118623
1992	3.994310892101932
1993	3.9506846264280595
1994	4.32945477751286
1995	4.515383181659366
1996	5.154953890807802
1997	5.224179185274422
1998	4.960330767173516
1999	5.170331760967752
2000	6.348438119944658
2001	6.3542517608861315
2002	6.9179105408728745
2003	6.520023999825492
2004	7.396519507507391
2005	8.266277655575369
2006	9.319726347990853
2007	9.583627161530215
2008	9.192274411925283
2009	8.577670662923344
2010	8.39553782920462
2011	11.05547480021781
2012	11.136603669795072
2013	10.50156230369911
2014	11.8542808453924
2015	10.440302645500873