Year	constant 2011 PPP $ per kg of oil equivalent
1990	10.9037082278403
1991	10.9308622254093
1992	11.1621068463111
1993	11.2806503145923
1994	10.8699231794898
1995	10.6048896575698
1996	10.5262563968653
1997	10.0915334186164
1998	10.2305206684784
1999	10.5750359201246
2000	11.0356135540189
2001	10.7525773778956
2002	10.8433332964513
2003	11.0845647499657
2004	11.4255319540656
2005	11.7987139008822
2006	12.0002783033446
2007	12.2063477136467
2008	12.387535242584
2009	12.1960475246607
2010	12.6585517954638
2011	13.0123879066164
2012	12.6283825985724
2013	13.8475671904225
2014	13.8820392143394