Year	PPP $ per kg of oil equivalent
1990	6.118940876011378
1991	6.349784987607957
1992	6.483976513006336
1993	6.7232596607670425
1994	6.82945889120036
1995	6.999024542223221
1996	7.067125620382553
1997	7.284815357131573
1998	7.309802356438677
1999	7.3158076800097485
2000	7.653230494023038
2001	7.769256511732833
2002	7.764445648706142
2003	7.884626183276031
2004	8.23978543940235
2005	8.551445658911723
2006	8.99480080490791
2007	9.575522026883254
2008	9.851535188081217
2009	9.863654487800702
2010	10.070127967345769
2011	10.642918259421078
2012	10.892770718241291
2013	11.08329619052225
2014	11.23168889752501