Year	PPP $ per kg of oil equivalent
1990	1.1994629601022087
1991	1.2233834347238957
1992	1.3700038527082758
1993	1.5964346278378012
1994	1.5890189859027173
1995	1.7865979845288664
1996	1.7038844322848399
1997	1.989051132391827
1998	2.286909082711235
1999	2.429290464927134
2000	2.792092227360469
2001	2.913249212781516
2002	3.4145259305913953
2003	3.457912418334088
2004	3.7336971757980315
2005	4.324803259527126
2006	5.124509534186327
2007	5.231402859998986
2008	5.554207548508793
2009	5.611777797424527
2010	5.1188930482426285
2011	5.79490454413174
2012	6.2275112514019755
2013	5.940484667220873
2014	6.302608894859652
2015	6.991047872609869