Year	PPP $ per kg of oil equivalent
1990	3.067871708035367
1991	3.140576606130823
1992	3.251908327681816
1993	3.3562780341714156
1994	3.49622360031913
1995	3.619036010176981
1996	3.7356756938787417
1997	3.928920332566255
1998	4.119975493898673
1999	4.26373009550358
2000	4.413180547469527
2001	4.643886064462719
2002	4.747450176236017
2003	4.942385484863359
2004	5.159663221813675
2005	5.485991840593717
2006	5.869764780107111
2007	6.051024988269954
2008	6.319680692652698
2009	6.503864888004687
2010	6.617768861887472
2011	6.917091906673304
2012	7.306757884882221
2013	7.511363387112014
2014	7.703935196759979
2015	8.102545682620104