Year	PPP $ per kg of oil equivalent
1990	6.7725028590170675
1991	6.69743069429216
1992	6.596429197389162
1993	6.323548052687692
1994	6.119565096759341
1995	6.175943740094442
1996	6.678388887410996
1997	6.4520725024735945
1998	7.041651469730924
1999	7.117543698509097
2000	7.744843718789871
2001	7.547968900607505
2002	7.726518840733717
2003	7.835569870832687
2004	8.070048515201442
2005	7.969428596791968
2006	8.33509178078897
2007	8.684525213341612
2008	8.644624701738996
2009	8.594788799853418
2010	9.054884728223477
2011	9.1168597340872
2012	8.944805058886898
2013	8.820654315531108
2014	8.366493357242833