Year	constant 2011 PPP $ per kg of oil equivalent
1990	10.2655673004649
1991	10.3752858253506
1992	10.5633492040929
1993	10.4824123061388
1994	11.328932830609
1995	11.1476163077081
1996	11.026836054678
1997	11.1691058283946
1998	11.0048896011311
1999	11.4161371906939
2000	12.726594097659
2001	11.7330417852803
2002	11.6460103187804
2003	11.576628404042
2004	11.1481272633169
2005	9.99576371988073
2006	10.1075076587209
2007	10.1049693835351
2008	10.4238379901613
2009	10.6637145175807
2010	11.4304935717142
2011	11.0839176641573
2012	11.0221947804434
2013	11.7495089958003
2014	12.1238868887588