Year	PPP $ per kg of oil equivalent
1990	3.291824692892225
1991	3.1478906336744954
1992	3.4053274401075226
1993	3.3884364142044974
1994	3.678493262557866
1995	3.669896939733253
1996	3.6335433060468283
1997	3.886764310863682
1998	4.155548092142857
1999	4.36551685945999
2000	4.842321835070227
2001	5.2580727107223515
2002	5.76409104616176
2003	5.9991690990037165
2004	6.307665252460903
2005	6.264405663634591
2006	6.775484832400627
2007	7.185238885439242
2008	7.8590361896155425
2009	8.362072202062697
2010	8.462175258028125
2011	9.210594909813844
2012	9.835941761565293
2013	10.804819970825424
2014	11.100266511830872
2015	11.015860418699447