Year	constant 2021 PPP $ per kg of oil equivalent
1990	13.996189745034517
1991	14.292131770370636
1992	13.715655683414289
1993	13.376786505712916
1994	12.719566753798706
1995	11.864560222933934
1996	11.516775676565372
1997	11.082911872791755
1998	11.515812581425024
1999	11.768360719367335
2000	10.783588660317989
2001	14.092819573806901
2002	12.047698274175106
2003	11.902371250468615
2004	12.38398458630401
2005	11.856555401338282
2006	9.927614153682375
2007	12.74119802081892
2008	12.716503941485042
2009	12.617875534322392
2010	12.060998856980094
2011	12.015048061242632
2012	10.98605062299786
2013	11.6695059734517
2014	11.526314968950722