Year	PPP $ per kg of oil equivalent
1990	1.6446150744315378
1991	1.7177936380590977
1992	1.8686935925898467
1993	2.0449220887997575
1994	2.1117190019043512
1995	2.2293241707863394
1996	2.4117949106274597
1997	2.5386972960216356
1998	2.646050215880208
1999	2.96686555283578
2000	3.3459623267123826
2001	3.898211349330215
2002	4.289954082818578
2003	4.591737026324864
2004	5.075505010433597
2005	5.924840774113279
2006	6.80976341274301
2007	7.549429626743064
2008	8.800558201478122
2009	10.332459547793572
2010	11.70662854206362
2011	12.349412640857672
2012	12.239637986896009
2013	12.53737762507111
2014	11.487008031621208