Year	PPP $ per kg of oil equivalent
1990	3.1192959834182665
1991	3.1402044243761886
1992	3.254941346874972
1993	3.2279926273423807
1994	3.332867861816324
1995	3.4666568608103865
1996	3.5479813923058012
1997	3.595208217785434
1998	3.6078029932289546
1999	3.6070164271128364
2000	3.7606096585949604
2001	3.9132103883653397
2002	4.129182588829828
2003	4.3103988815494025
2004	4.679806305079908
2005	5.057195065914652
2006	5.400525531859182
2007	5.696222350159946
2008	5.8928698112147995
2009	6.363724652441233
2010	6.541478707321995
2011	6.665075583784628
2012	6.808127235530011
2013	7.281585685395292
2014	8.35425291677818