Year	PPP $ per kg of oil equivalent
1990	5.131622609893879
1991	5.435573710959398
1992	5.621582009797491
1993	5.5728283564476575
1994	5.671524937177175
1995	5.81914948755725
1996	5.90346477902373
1997	5.909075512481546
1998	5.998050878759844
1999	5.971925663055134
2000	6.201657984269915
2001	6.467334890660506
2002	6.6633979090662985
2003	6.8510513391067365
2004	7.076281472820844
2005	7.550454251903168
2006	7.923567492720989
2007	8.067648574020298
2008	8.54082355797427
2009	8.760192989713163
2010	8.871520305843836
2011	9.227799716635348
2012	9.698065729643318
2013	9.926498659625183
2014	10.280924502763753