Year	PPP $ per kg of oil equivalent
1990	4.137528317926159
1991	4.467632710450498
1992	4.425932092419812
1993	4.942766370835052
1994	5.020118494368889
1995	4.928640237882541
1996	4.756797699593984
1997	4.783997145283935
1998	4.546210478654699
1999	4.532326658448555
2000	4.420265264349421
2001	4.566312525335385
2002	5.07213484682153
2003	5.146753635065836
2004	5.294277449344042
2005	5.576506235369851
2006	5.279187595576167
2007	5.46883112084224
2008	6.571066962612529
2009	7.373216614409187
2010	8.305778456034032
2011	8.084303558473488
2012	8.382193467113494
2013	8.347838074900812
2014	8.686633541482992