Year	PPP $ per kg of oil equivalent
1990	6.00571499675685
1991	6.032749654383577
1992	6.555999751561087
1993	6.670398899373252
1994	6.995439485643216
1995	7.019559905799924
1996	6.8573019376005275
1997	7.160318111845514
1998	7.396097166141944
1999	7.685954193903177
2000	8.228469949462037
2001	7.905259887907181
2002	8.262207425509743
2003	8.089847617664354
2004	8.427747536548736
2005	8.570097728316115
2006	9.233551419601657
2007	9.81184703853715
2008	10.24670245476873
2009	10.772851824169923
2010	10.3678412318645
2011	11.334487598645028
2012	11.952694109898266
2013	12.227993357684198
2014	12.967170741225953
2015	13.12157238856839