Year	PPP $ per kg of oil equivalent
1990	3.695664350857641
1991	3.804176958595507
1992	3.7608015057772675
1993	3.769522230648098
1994	3.9083314688295254
1995	3.976094123250479
1996	4.06815596447173
1997	4.10901394817825
1998	4.1372995669421115
1999	4.200409138353839
2000	4.173958748776269
2001	4.369777984295684
2002	4.403357137346851
2003	4.522858288668095
2004	4.643215583482906
2005	4.8959883096152454
2006	5.153876236187875
2007	5.535434925562252
2008	5.462707351591022
2009	5.361986539460166
2010	5.615263021269158
2011	5.901947923693054
2012	6.195741456267304
2013	6.550934126776087
2014	6.547138285807161