Year	PPP $ per kg of oil equivalent
1990	2.1132314281441325
1991	2.367613144387289
1992	2.572401879677096
1993	2.7389999959970748
1994	2.9604100974417946
1995	3.0777418225679467
1996	3.2946149474836015
1997	3.5397989625453508
1998	3.6054894676978533
1999	3.7775898914475405
2000	3.9881032776066254
2001	4.191680856340719
2002	4.306595646126008
2003	4.2646999004532455
2004	4.238664958506681
2005	4.387199400915791
2006	4.629357637777819
2007	4.955460694518113
2008	5.297506039738707
2009	5.392892511977492
2010	5.452413789011247
2011	5.687343644890736
2012	6.003838166962178
2013	6.2057252630125666
2014	6.382319650399561