Year	PPP $ per kg of oil equivalent
1990	3.65732429578977
1991	3.635236387036672
1992	3.6793773470853477
1993	3.6438716095512658
1994	3.756831968375059
1995	3.800351692930283
1996	3.863048842590928
1997	3.96393534075825
1998	4.0853953260372675
1999	4.013376855359061
2000	4.22452421387537
2001	4.33500102060235
2002	4.671920683018967
2003	4.8052782321358185
2004	5.1810585581209265
2005	5.427799413804527
2006	5.802764692790918
2007	6.072791284825816
2008	6.227336691204578
2009	6.660507899460279
2010	6.7495819684393705
2011	6.887439282757415
2012	6.93720664468593
2013	7.296726324663199
2014	7.846217337385369