Year	PPP $ per kg of oil equivalent
1990	3.134630926571651
1991	3.3327747986957776
1992	4.358620808603205
1993	4.988848834912158
1994	5.189125484804389
1995	6.391689559361886
1996	6.653642683313873
1997	7.06495185758578
1998	7.080282649110518
1999	6.025280126862601
2000	6.651754342073439
2001	7.200881163116293
2002	7.199205741077435
2003	7.714521692357838
2004	7.586925739092832
2005	8.15086984486007
2006	9.28966990525798
2007	10.715247889211211
2008	11.57671371027298
2009	12.033871350776149
2010	13.202505879783962
2011	13.343253118353212
2012	15.30132252354436
2013	13.191095007426977
2014	13.925877862730518