Year	PPP $ per kg of oil equivalent
1990	3.1148130287250075
1991	3.3261001188127843
1992	3.5424861777000496
1993	3.6967545340682775
1994	3.873564715746637
1995	3.941751791529632
1996	4.176963529919685
1997	4.408226625702765
1998	4.475706930304815
1999	4.602514692265498
2000	4.864475877333956
2001	5.00509010617103
2002	5.097049796881939
2003	5.035449855710854
2004	5.0951631396602455
2005	5.261322530116555
2006	5.540754106774046
2007	5.857239253441088
2008	6.154981393170382
2009	6.208705708082769
2010	6.2991029125852664
2011	6.554901019267119
2012	6.76436022952454
2013	6.956867299545752
2014	7.142330418656021