Year	PPP $ per kg of oil equivalent
1990	3.5142177431673223
1991	3.5223310865184168
1992	3.417406202474393
1993	2.956318521956702
1994	3.0699743741374466
1995	3.211550563854769
1996	3.174403594965854
1997	3.747483597462191
1998	3.4637619928263543
1999	3.148721895410674
2000	3.201630914579645
2001	3.3084988770340495
2002	3.368795745724908
2003	3.4716134664805343
2004	3.493267781570956
2005	3.369906990773004
2006	3.5733633866577286
2007	3.493887453236948
2008	3.5536038308198115
2009	3.100060720335129
2010	3.3218505832202054
2011	3.567262342134229
2012	3.740937094095775
2013	3.897020541147209
2014	4.081455464809982