Year	PPP $ per kg of oil equivalent
1990	3.292597581962971
1991	3.4739104139918666
1992	3.6726714903777706
1993	3.8146793287462817
1994	3.9948474505668097
1995	4.081927196427881
1996	4.312092426284649
1997	4.510687378517103
1998	4.596877101507021
1999	4.729951533635859
2000	4.984874527474207
2001	5.151260248149235
2002	5.257753849942385
2003	5.284587276602112
2004	5.39578579951171
2005	5.609476727280211
2006	5.915915992472065
2007	6.2401135332846644
2008	6.511381937196311
2009	6.582602730808154
2010	6.710722600349532
2011	6.955915102099505
2012	7.209648491808983
2013	7.44506756799073
2014	7.613728752106876