Year	constant 2011 PPP $ per kg of oil equivalent
1990	10.5624420893725
1991	10.6576428802357
1992	10.8411656264215
1993	10.9219799037463
1994	11.1629472849274
1995	11.5418860178459
1996	11.4987590534356
1997	12.2575526072947
1998	11.7714007501871
1999	12.6094223709577
2000	12.916323078263
2001	13.1872569391918
2002	13.7874374497259
2003	14.0327863612164
2004	14.6304498656086
2005	14.7053551565346
2006	14.9398647015187
2007	16.0626728593698
2008	15.8420056060499
2009	15.4659992265434
2010	15.880099364456
2011	17.0225725948557
2012	17.5224873612017
2013	17.1744504470154
2014	17.7993933236814