Year	PPP $ per kg of oil equivalent
1990	6.110433057626661
1991	6.42303041650023
1992	6.446606802168518
1993	6.039266495914695
1994	5.461654447569501
1995	5.455779006282209
1996	6.125439791344996
1997	5.642915213054026
1998	5.719795643762812
1999	5.215927301510271
2000	5.792685000357035
2001	5.589932759729731
2002	5.931835936600368
2003	6.35902622876472
2004	6.247514230603753
2005	5.9911587604179575
2006	6.204614400305636
2007	6.5142704244361145
2008	6.211406989339899
2009	6.324803572253632
2010	6.770993534916886
2011	6.956239677983172
2012	5.978068873680387
2013	5.65977279593046
2014	5.297017335041274