Year	PPP $ per kg of oil equivalent
1990	1.5678204962888025
1991	1.4779837247183867
1992	1.5655025850473312
1993	1.5515773491943157
1994	1.4339632349947284
1995	1.3017015109911656
1996	1.3021809660243433
1997	1.342862016980921
1998	1.4087180133455983
1999	1.4324975478039035
2000	1.566075050911045
2001	1.7383313433706373
2002	1.8389641942605113
2003	1.92538525551978
2004	2.2225302753870686
2005	2.378671125923358
2006	2.744134934847061
2007	3.005915729501284
2008	3.242147458089661
2009	3.2543311960507237
2010	2.9654238176084204
2011	3.3394798627775812
2012	3.6030223337483767
2013	4.3306108025528465
2014	4.339307422559552