Year	PPP $ per kg of oil equivalent
1990	8.65727788262635
1991	9.033781089895728
1992	8.770176258690094
1993	9.333270135423252
1994	9.310361994836917
1995	9.5324525301445
1996	9.451752056315053
1997	9.847392139347251
1998	9.217254638966736
1999	9.854993873854479
2000	10.219511673322321
2001	9.270253622190907
2002	10.592082572929156
2003	11.242643071229393
2004	12.584693693763876
2005	12.475358789259667
2006	13.077430360202206
2007	15.366864020591603
2008	17.163095887788067
2009	15.841671659636594
2010	15.857310198918865
2011	16.602763238176024
2012	18.24035349757271
2013	21.254594188690614
2014	22.656686143388445