Year	PPP $ per kg of oil equivalent
1990	7.840336292171966
1991	7.9107721458585685
1992	8.051767091099705
1993	8.443628743613857
1994	8.655267822225138
1995	9.00776750365329
1996	9.068779450800188
1997	9.282195231421486
1998	9.51594929782633
1999	9.793904655703326
2000	10.5428075365957
2001	10.296736989646906
2002	10.891330164351507
2003	10.936360946282681
2004	11.37960039961951
2005	11.904314675656394
2006	12.786297481844986
2007	14.931744992807262
2008	15.374856494564872
2009	15.213558881236478
2010	16.260017510545893
2011	17.936877660211223
2012	18.55884807147405
2013	18.66050606652225
2014	20.72495248010579
2015	22.04845527393609