Year	constant 2021 PPP $ per kg of oil equivalent
1990	14.743787308534307
1991	14.337810919935126
1992	13.114184818493246
1993	12.638800013913045
1994	12.43429738555779
1995	13.370529412481359
1996	12.823502835736134
1997	13.780200086931261
1998	14.404293489494993
1999	12.222284833528288
2000	12.611873782786237
2001	12.83129479884266
2002	11.676819791990182
2003	11.76802071831955
2004	8.616275170460408
2005	8.41311581074651
2006	8.796200924904367
2007	8.262495536731645
2008	8.613763516154055
2009	9.738243005644927
2010	9.600459858969094
2011	7.924296156063455
2012	7.8656891645354
2013	8.134384787981999
2014	8.675391666498355