Year	PPP $ per kg of oil equivalent
1990	7.492483882319533
1991	7.9814994205588405
1992	8.30567921113757
1993	8.621378701877578
1994	9.683144214338485
1995	10.103186681582613
1996	9.54292130656171
1997	9.967080623958013
1998	10.380578018034473
1999	10.28254094693696
2000	10.120509497111325
2001	10.53908452182958
2002	10.92597841147092
2003	11.145216329531532
2004	11.908873400008998
2005	12.755137374707564
2006	14.029112184464777
2007	15.092960378689694
2008	16.559906283124622
2009	17.382394982898873
2010	17.647654815573794
2011	18.232065511262906
2012	19.278281791229873
2013	23.08807783824442
2014	22.73588212040306