Year	PPP $ per kg of oil equivalent
1990	2.0754391843210755
1991	2.1609363112064206
1992	1.8885904834433092
1993	2.1448884972994327
1994	1.8132443796601425
1995	1.9691504003017815
1996	2.1960043072918674
1997	2.3787555548094255
1998	2.4352893709704793
1999	2.737070455404926
2000	3.0887469111469357
2001	3.1652590515263013
2002	3.416425875795058
2003	3.421505907071666
2004	3.7548544252114104
2005	4.019693544119356
2006	4.401459718914343
2007	4.785454389801639
2008	5.277618699792475
2009	5.2552105456289135
2010	5.160366290771197
2011	5.662453915484242
2012	6.0754547241237455
2013	7.668636367672163
2014	7.481471102166954