Year	PPP $ per kg of oil equivalent
1990	3.3421443234397445
1991	3.3235076593519604
1992	3.2852897086841466
1993	3.2124161185127216
1994	3.2034001321320575
1995	3.319883821508627
1996	3.476032042935825
1997	3.6117244896477447
1998	4.157281319521641
1999	4.416914189237962
2000	4.648550136341158
2001	4.703659924871338
2002	4.8637284802500655
2003	4.629339187598976
2004	5.293308500349094
2005	5.585284210603913
2006	6.011893140067831
2007	6.343227362983291
2008	6.547265705589177
2009	6.658308392949083
2010	6.737912215646137
2011	6.804232548523564
2012	6.7983844991314
2013	7.106343230470786
2014	7.374822783608851