Year	PPP $ per kg of oil equivalent
1990	6.406895429226583
1991	6.9883887554072235
1992	6.3833609600760335
1993	6.639971349206771
1994	7.132090133711934
1995	7.60991317962031
1996	8.405887597255148
1997	8.828268305294383
1998	7.943700303097229
1999	8.555379339815302
2000	8.583821953470121
2001	8.697166026459332
2002	9.222688952517975
2003	9.871663258421984
2004	10.587182593380604
2005	11.062960375902541
2006	11.95762253043265
2007	12.572071293106786
2008	12.502723427789388
2009	11.579059632174708
2010	11.790954001603179
2011	13.382674406602488
2012	11.208754591935108
2013	11.506993017041044
2014	11.996147526200556