Year	PPP $ per kg of oil equivalent
1990	4.585714778351264
1991	4.532504400080226
1992	4.792180365821519
1993	4.795757407240576
1994	5.210938323427523
1995	5.215240499082534
1996	5.093435136838612
1997	5.492305825921813
1998	5.626535338961014
1999	5.894833011461992
2000	6.30977755178099
2001	6.476243955330003
2002	6.750467862736923
2003	6.596715424042307
2004	6.755710852809718
2005	7.113939693594802
2006	7.7511518380850255
2007	8.292755788210375
2008	8.537776821271848
2009	8.860976212664447
2010	8.936530858920088
2011	9.732240917598697
2012	9.82082208316772
2013	10.310030504772339
2014	10.971047725797831
2015	11.06440955119141