Year	constant 2011 PPP $ per kg of oil equivalent
2000	4.10618715846018
2001	4.17377809300908
2002	4.13606835432764
2003	4.21555929758072
2004	4.27870319367334
2005	4.37164820028424
2006	4.47307721273362
2007	4.68127881363568
2008	4.80732309554262
2009	4.84295926340753
2010	4.92708273890651
2011	4.9380611517813
2012	4.93281763152724
2013	5.05276414960774