Year	PPP $ per kg of oil equivalent
1990	12.082173213567254
1991	12.727546948417997
1992	11.639520713069158
1993	12.76406781636725
1994	13.691509454103485
1995	14.369000887698034
1996	15.47853443631491
1997	17.204968777660962
1998	12.542230155386578
1999	10.634490511135443
2000	13.841970283573561
2001	13.655532154148398
2002	15.19094099834588
2003	15.517810757344803
2004	18.442073559459363
2005	20.645016142697287
2006	21.59720785315484
2007	21.984676588617326
2008	23.341599043943845
2009	21.762464675001233
2010	25.273028275907066
2011	25.04655725918472
2012	26.143918116291392
2013	27.531725805285205
2014	27.66575281894437