Year	PPP $ per kg of oil equivalent
1990	3.271087690871674
1991	3.5561946700428546
1992	3.6918177405758175
1993	3.784268066960471
1994	3.9278964127600995
1995	4.030779547759503
1996	4.2112487884979775
1997	4.397632299390155
1998	4.470807317694618
1999	4.5910969061932
2000	4.8016650192733605
2001	4.991341644203555
2002	5.110740007274376
2003	5.093254071290387
2004	5.095914676866778
2005	5.278849093608005
2006	5.516441402247134
2007	5.821163997704608
2008	6.114983906957743
2009	6.149570552119774
2010	6.176697667386382
2011	6.440843797621454
2012	6.753675448900187
2013	6.979058411834786
2014	7.166213712098085