Year	PPP $ per kg of oil equivalent
1990	7.957121303163132
1991	8.431334357235523
1992	8.743035287396344
1993	9.006021040645319
1994	9.75035308922056
1995	9.711198927279163
1996	10.258340893497337
1997	10.733505193538958
1998	10.817836587832973
1999	10.757764218366717
2000	10.737160657194094
2001	10.805967815411037
2002	11.246034783341583
2003	11.58417904885162
2004	12.18925112706901
2005	12.370681625994095
2006	12.50665794572918
2007	13.505034209731848
2008	14.178596650871789
2009	15.107101013332352
2010	15.106433363521418
2011	16.02022471304306
2012	16.1549094263074
2013	16.651844615351585
2014	17.158723952271714