Year	PPP $ per kg of oil equivalent
1990	2.709991182020262
1991	2.714894005281641
1992	2.7771170825119635
1993	2.715271516157144
1994	2.7520552319279052
1995	2.807727185949525
1996	2.9496285123869903
1997	3.0591179969496944
1998	3.113634012312087
1999	3.157461269169781
2000	3.3206691391812235
2001	3.4100094813435122
2002	3.579778433027486
2003	3.59998039135944
2004	3.7224081087765617
2005	4.026094846822789
2006	4.345055794615843
2007	4.55584546649969
2008	4.565795186221639
2009	4.573674567305783
2010	4.8099686819316565
2011	5.00551378418521
2012	4.992214603617071
2013	5.214509183415149
2014	5.390551471253457