Year	constant 2011 PPP $ per kg of oil equivalent
1990	15.7175731733784
1991	16.1513498714863
1992	14.6426458367902
1993	14.3854085245936
1994	16.8311862343849
1995	16.1120058517318
1996	16.034075109409
1997	16.7475131632262
1998	16.2917453620681
1999	15.2422353510698
2000	14.8864442121606
2001	14.1637794339858
2002	11.7040062351193
2003	10.1792488504781
2004	8.83155347714944
2005	7.84943534558268
2006	6.78257265599121
2007	6.45535860252387
2008	5.67974523426721
2009	5.19859259364376
2010	4.95600420216489
2011	6.59106710281366
2012	7.82837371723573
2013	5.66416810886276
2014	6.163934779419