Year	PPP $ per kg of oil equivalent
1990	0.6608994070240937
1991	0.688113979697364
1992	0.9349405225946681
1993	1.123755607597545
1994	3.2943904807218884
1995	3.7462041884970594
1996	5.036222732833038
1997	4.534227347005365
1998	4.302194420732857
1999	4.828884875636108
2000	3.9691279072073957
2001	4.2859328807456825
2002	4.519653914062207
2003	4.6713399086065905
2004	4.656707370994931
2005	4.8408547423036765
2006	5.267238864636084
2007	5.815945417483405
2008	5.685750946328635
2009	5.424856541372277
2010	5.343403663230695
2011	5.111367130991986
2012	5.557101687196373
2013	6.046668172829014
2014	5.088019299393185