Year	PPP $ per kg of oil equivalent
1990	3.4291311203332087
1991	3.4386131980263666
1992	3.57901306438812
1993	3.748191700429106
1994	3.9321633557914595
1995	4.08406463864122
1996	4.339983511144394
1997	4.418334011466228
1998	4.633103093080481
1999	4.83561034975179
2000	5.016981260758957
2001	5.301425671218955
2002	5.4264195433875475
2003	5.828913029575825
2004	6.133639401027971
2005	6.569832978395353
2006	6.952991019981251
2007	7.277266298553341
2008	7.287949068159866
2009	7.181934119521205
2010	7.545249442735103
2011	7.774589617616995
2012	8.126001815144622
2013	8.374173691313771
2014	8.260521719341394