Year	PPP $ per kg of oil equivalent
1990	4.622753200020398
1991	4.552899538451063
1992	4.463760119436283
1993	4.066289893160955
1994	4.08917189954654
1995	4.221970161023508
1996	4.3724777033581494
1997	4.520540376699268
1998	4.653223068577804
1999	4.894002549063196
2000	4.9833447682438266
2001	5.253876068955978
2002	5.4454035457912715
2003	5.627041046019295
2004	5.998781585082814
2005	6.2873439361006875
2006	7.059907508961675
2007	8.022377363825402
2008	8.336841146580241
2009	7.958932555558053
2010	8.226391143544673
2011	9.006282875842963
2012	9.19518244472588
2013	9.526619783254827
2014	9.92960505024449