Year	PPP $ per kg of oil equivalent
1990	8.949974704866731
1991	9.440066400957306
1992	8.923978878779472
1993	8.737862438618647
1994	9.215631448913134
1995	8.983125843773257
1996	9.780869775624021
1997	9.50165510351863
1998	10.110072206454083
1999	9.807313034038886
2000	10.235110358270484
2001	10.634801533508353
2002	11.02181671329229
2003	11.985714812744847
2004	10.84868472844961
2005	10.90785640686566
2006	11.918493948436096
2007	12.277370871641756
2008	12.736973269720927
2009	13.20039707044247
2010	13.182258012643937
2011	13.176272880266607
2012	13.23206443575286
2013	13.779428327669422
2014	13.221826639914635