Year	PPP $ per kg of oil equivalent
1990	5.50223094609193
1991	6.868415419474957
1992	8.07207700840988
1993	6.389711035384163
1994	6.439173911622174
1995	6.104336231146159
1996	6.560048431069698
1997	5.971630302609621
1998	6.3708366807805215
1999	6.142865732685579
2000	7.003410340284668
2001	6.9363932754353055
2002	7.332149161187833
2003	7.710013940342319
2004	8.35910524251761
2005	9.282426025229858
2006	10.219660586865073
2007	13.019343496851826
2008	11.260604956462837
2009	10.201870542808011
2010	11.621230610218529
2011	12.024184914124444
2012	11.770501912901345
2013	13.25168450407205
2014	13.670209682667563