Year	PPP $ per kg of oil equivalent
1990	5.090306820111075
1991	5.571212246899051
1992	5.848400571349264
1993	6.459554944272878
1994	6.563856564766338
1995	6.418327363595762
1996	6.651585142268092
1997	7.088151615027938
1998	7.197619819941662
1999	6.9335935261344614
2000	6.952285032027179
2001	7.143623887551062
2002	6.651125007692454
2003	6.898945914757604
2004	7.070687264325296
2005	7.890475137629935
2006	8.078121560195815
2007	8.928670086179952
2008	8.992909766289753
2009	8.75487313024222
2010	9.367421282986014
2011	9.898423043128087
2012	10.135203511230982
2013	10.222666039052433
2014	9.679852181724787