Year	PPP $ per kg of oil equivalent
1990	6.343100562759662
1991	7.040694143734778
1992	6.751545476753972
1993	6.864516775543761
1994	7.061358847692246
1995	7.328286509923791
1996	7.688931446647375
1997	7.694563909242715
1998	7.907623354975364
1999	8.517972956801902
2000	8.861466252018873
2001	8.658877768008873
2002	9.097660425219562
2003	8.360601784243663
2004	9.233574598182132
2005	9.628227803089143
2006	9.133850112585263
2007	9.719841790834371
2008	8.946550983187333
2009	9.71110131148838
2010	9.628547067927265
2011	10.456336315492328
2012	10.536312479069572
2013	12.104253032884186
2014	12.57565114521785
2015	12.910684902167374