Year	PPP $ per kg of oil equivalent
1990	7.208110895423435
1991	7.384699633546438
1992	7.663935798863394
1993	7.819618445745271
1994	8.262781639926343
1995	7.99451162291723
1996	8.243790724586658
1997	8.422026143374842
1998	8.589550631581186
1999	8.657319188049575
2000	8.98874427298875
2001	9.283525090422588
2002	9.46132738454774
2003	9.215171838789361
2004	9.323717507138086
2005	9.37284568402278
2006	10.21896461496198
2007	10.84239846890706
2008	11.505265798974683
2009	12.0567477293792
2010	11.994994981563508
2011	12.939453994240118
2012	13.467068018610211
2013	14.078342180684336
2014	14.990728410339461
2015	14.868264788683156