Year	PPP $ per kg of oil equivalent
1990	5.6694361145693195
1991	5.96607617088541
1992	6.234120522650929
1993	6.187733238532406
1994	6.787383504395692
1995	6.799381826953146
1996	7.203885369440408
1997	7.423059581716229
1998	6.666913182099196
1999	6.505517080483349
2000	6.439804968097368
2001	6.668046445158163
2002	6.8230271841647
2003	7.2696961797826365
2004	7.355065211741223
2005	7.878021014635381
2006	8.370823508100118
2007	9.186406516071305
2008	9.733898073988597
2009	9.479710329803774
2010	9.700301400730833
2011	10.911885759695249
2012	11.360842580691063
2013	11.604933009398971
2014	11.553725040675475