Year	constant 2021 PPP $ per kg of oil equivalent
1990	13.071136211310323
1991	12.06594577939286
1992	12.37090493197591
1993	12.436037132466959
1994	12.292784469991426
1995	12.108020400725033
1996	12.772000802485657
1997	11.902786852006063
1998	11.877907043508793
1999	11.69449513768636
2000	11.30421799945018
2001	10.89996753987727
2002	10.85918196010362
2003	10.565394968074884
2004	10.746843407166265
2005	10.725926888000819
2006	10.655695861481068
2007	11.471776242121381
2008	11.66916866285682
2009	12.196036547746202
2010	12.348916837487522
2011	12.69229347409752
2012	13.26284800117892
2013	14.355248241775293
2014	14.326729428845303