Year	PPP $ per kg of oil equivalent
1990	5.624859041596236
1991	5.163127307755212
1992	5.215149208501574
1993	5.425665547956433
1994	6.083233199985493
1995	6.304614146063771
1996	6.38218617481942
1997	5.986740104923207
1998	5.9000511128952295
1999	6.269333603021723
2000	6.120126790915393
2001	6.044331579466003
2002	6.258549093520489
2003	6.301648534691501
2004	6.425434986760852
2005	6.435078780002389
2006	6.965772614184081
2007	6.945072198023994
2008	7.09906086964365
2009	7.403675727697524
2010	7.885579294443735
2011	8.127134904020842
2012	8.624746888219713
2013	7.959090160343983
2014	8.317639644665253