Year	PPP $ per kg of oil equivalent
1990	3.272417653024375
1991	3.450010718617616
1992	3.6440867843974623
1993	3.784871467618233
1994	3.9602337110070533
1995	4.0476665555158995
1996	4.274973160344678
1997	4.473445313579534
1998	4.558300166161322
1999	4.687611009560173
2000	4.941191879778953
2001	5.105419492992283
2002	5.211599450614243
2003	5.24169320831572
2004	5.357176135584095
2005	5.572378519283744
2006	5.877295813087532
2007	6.2017173325039865
2008	6.470528207921159
2009	6.53907792506538
2010	6.67094690149885
2011	6.9133317766651805
2012	7.159203154948128
2013	7.390465570284389
2014	7.556385940952799