Year	PPP $ per kg of oil equivalent
2005	4.761556821725242
2006	5.465531666522306
2007	6.463757629809786
2008	6.681051354510969
2009	7.909515922173283
2010	7.181773983451799
2011	7.971018512430629
2012	8.09861351752163
2013	9.408519811845318
2014	9.991813062424338