Year	PPP $ per kg of oil equivalent
1990	6.326491525066709
1991	6.688364069945041
1992	6.723028433516124
1993	6.858562997960876
1994	6.951541243403989
1995	7.182709812028183
1996	7.317999433774184
1997	7.5160967131162675
1998	7.546127837671003
1999	7.725561459532578
2000	7.7867881774406165
2001	8.130363593202189
2002	8.705976518566352
2003	8.96244019897442
2004	9.39018911821669
2005	9.290609669327328
2006	10.409346953603666
2007	10.723779904041669
2008	11.238785415375595
2009	11.457406115339948
2010	11.24377832539574
2011	10.661979148027678
2012	10.365680662097766
2013	12.211710537652468
2014	12.535942486168116
2015	12.2637449271222