Year	constant 2011 PPP $ per kg of oil equivalent
1990	12.0615315945351
1991	11.9680542512806
1992	12.0705219520798
1993	13.2021064335772
1994	12.8617116994746
1995	11.2305797034598
1996	10.8473158215436
1997	10.9009208078662
1998	10.9555781103202
1999	11.5989768250811
2000	10.5828204752488
2001	10.3732246948785
2002	11.0649629814263
2003	11.1996835922299
2004	12.549040423323
2005	12.6617826105963
2006	13.1607876547865
2007	11.8878767065309
2008	13.7245662508748
2009	11.5874533647391
2010	11.8674898073479
2011	12.0887570566953
2012	12.9358744116952
2013	12.6001794794951
2014	12.2255889626884