Year	constant 2011 PPP $ per kg of oil equivalent
1990	15.9601753496679
1991	13.9397715977508
1992	13.8105245780929
1993	16.593339389727
1994	16.9611337126204
1995	15.8354567485631
1996	16.2282361530343
1997	16.071456092761
1998	15.9454504120349
1999	14.6603321417249
2000	14.6627749896682
2001	13.7228781036509
2002	14.723889711364
2003	13.7486703462104
2004	13.0968523209755
2005	12.9838909522704
2006	12.5127237774656
2007	13.2132076987983
2008	12.9872429984798
2009	12.1564342776435
2010	13.498952869709
2011	13.951889625062
2012	15.7959115615847
2013	11.983639981398