Year	constant 2021 PPP $ per kg of oil equivalent
2000	5.993110991851018
2001	6.063728264515826
2002	5.998532657941676
2003	6.085430571112167
2004	6.199435488419578
2005	6.297487007210938
2006	6.409596247483916
2007	6.616531690231801
2008	6.742677931509449
2009	6.738505788909974
2010	6.873069170889873
2011	6.857083468820899
2012	6.706482544121826
2013	6.855022393282772