Year	PPP $ per kg of oil equivalent
1990	5.153130362829964
1991	5.853782260752239
1992	6.339113319164193
1993	5.299361222670178
1994	6.306169305281501
1995	7.44051979937953
1996	7.979815186884546
1997	7.56487170711817
1998	9.04736715521716
1999	8.715418508723566
2000	10.601026771876837
2001	9.251917097260307
2002	10.788906869175635
2003	10.104028076960766
2004	10.425758240494616
2005	10.226927933696894
2006	11.344485507541277
2007	11.622442657643651
2008	12.97896496224265
2009	14.120538865826875
2010	14.270390306349032
2011	14.534274220613588
2012	14.467258782863292
2013	17.9092791894384
2014	19.276731260964183