Year	PPP $ per kg of oil equivalent
1990	3.2788877314601357
1991	3.331170297461947
1992	3.4358754513754692
1993	3.487403406016918
1994	3.582557771127959
1995	3.7147901644412626
1996	3.81811139912536
1997	3.9342754055126408
1998	3.978212757736526
1999	4.015001897094549
2000	4.226806429722956
2001	4.380987215700316
2002	4.5463953847248275
2003	4.73012119436169
2004	5.07794656859202
2005	5.444646070157962
2006	5.805028684591086
2007	6.135325277597781
2008	6.378403608873154
2009	6.695752813476646
2010	6.917597050339735
2011	7.07358422226381
2012	7.241670431736271
2013	7.642629727685509
2014	8.374236189783604