Year	constant 2011 PPP $ per kg of oil equivalent
1990	7.25023559449763
1991	7.61681738322206
1992	7.22215426606409
1993	7.77617151843542
1994	6.55111832047462
1995	7.25906199147839
1996	6.79693470360079
1997	7.26230996898829
1998	6.91746296180093
1999	6.82260219869075
2000	6.88383675452383
2001	6.87778928004617
2002	5.77564572206092
2003	5.79343140962801
2004	6.43267882611251
2005	7.11081831107821
2006	7.01299533994211
2007	8.24584278711796
2008	7.76212258467414
2009	7.49783901385221
2010	6.63532985339832
2011	7.44557710833278
2012	7.23324821679481
2013	7.7887143311874