Year	constant 2021 PPP $ per kg of oil equivalent
1990	13.438487877293195
1991	13.325225134999057
1992	13.115975431213837
1993	13.425912585071625
1994	13.49977782217228
1995	13.604301567373783
1996	13.202578477873226
1997	12.991278901424101
1998	12.729813817211648
1999	12.505919159946119
2000	13.002378685394625
2001	12.957044351660297
2002	13.008431196505438
2003	12.944065150913428
2004	12.968453171154364
2005	13.054920055789209
2006	13.116195141212888
2007	13.165350570178889
2008	13.105763263507233
2009	13.531618464357788
2010	13.158975764167007
2011	13.471091229858846
2012	13.159743087284195
2013	13.001858202362989
2014	12.657460437851986