Year	constant 2011 PPP $ per kg of oil equivalent
1991	12.7484838659611
1992	12.8398049380591
1993	11.7386991424774
1994	11.0813365455135
1995	10.5136014417251
1996	10.0989775368073
1997	10.2962170612646
1998	10.1925511124099
1999	10.5721496133185
2000	11.507035906498
2001	9.81959214573348
2002	11.1150588660889
2003	11.1173381062744
2004	11.9041161475777
2005	11.2606791066454
2006	12.0358120267869
2007	12.3239585165445
2008	11.8782396273465
2009	11.7024508259111
2010	11.9513386777869
2011	12.1653225513644
2012	12.3338753935045
2013	12.3450889592498
2014	12.6276364572666