Year	PPP $ per kg of oil equivalent
1990	3.4815235969483442
1991	3.6299014463632417
1992	3.793399106135046
1993	3.910062403308825
1994	4.093688100275089
1995	4.211134686331001
1996	4.351448338568692
1997	4.559301337338695
1998	4.692967969197024
1999	4.8227665094918
2000	5.067560030423293
2001	5.249406045086144
2002	5.391417839190849
2003	5.496444399935926
2004	5.690087603704689
2005	5.965082641829588
2006	6.3498795754897515
2007	6.690702233063235
2008	6.989047786670752
2009	7.0911985944607085
2010	7.15837923572853
2011	7.513149129769149
2012	7.767321427857539
2013	8.042743432260618
2014	8.272707068386364