Year	constant 2021 PPP $ per kg of oil equivalent
1995	4.76192874981307
1996	4.821425806517917
1997	4.934685944999257
1998	4.537709526774658
1999	5.10788360665568
2000	5.658007396564276
2001	6.087315280888555
2002	5.571267830192142
2003	5.8683219988925766
2004	7.861292125882005
2005	8.782053863435644
2006	9.74657918964742
2007	10.59147586924888
2008	11.265907138377772
2009	7.742488133351569
2010	7.86580063704458
2011	8.05034462383196
2012	8.291716722463804
2013	8.620972171037046
2014	8.652318847295637