Year	constant 2011 PPP $ per kg of oil equivalent
1990	4.81374147687338
2000	3.42564691175146
2001	3.25241781521248
2002	3.30451652653871
2003	3.28230027330261
2004	4.30873887770914
2005	4.03901729644698
2006	3.9349763172102
2007	3.89036298218842
2008	3.20992874088054
2009	3.13302103905696
2010	3.04931236153148
2011	3.10091738025095
2012	3.19526620359118
2013	3.19534773745272
2014	3.19941661190598