Year	PPP $ per kg of oil equivalent
1990	6.772502859017066
1991	6.69743069429216
1992	6.596429197389161
1993	6.323548052687692
1994	6.11956509675934
1995	6.175943740094443
1996	6.678388887410996
1997	6.452072502473594
1998	7.041651469730923
1999	7.117543698509097
2000	7.744843718789871
2001	7.547968900607505
2002	7.726518840733715
2003	7.8355698708326855
2004	8.070048515201442
2005	7.969428596791969
2006	8.335091780788972
2007	8.684525213341614
2008	8.644624701738996
2009	8.594788799853418
2010	9.054884728223474
2011	9.1168597340872
2012	8.944805058886898
2013	8.820654315531108
2014	8.366493357242833