Year	PPP $ per kg of oil equivalent
1990	1.9519226316735492
1991	2.008980509001684
1992	1.8104807513262036
1993	1.9576679401813335
1994	2.1998994724194176
1995	2.2095554577762035
1996	2.4936100338997935
1997	2.6307790974994
1998	2.6748618528665853
1999	2.5228835255863955
2000	2.6458401045641655
2001	2.751775155471072
2002	2.591483236001741
2003	2.2936476528188727
2004	2.2706686119735275
2005	2.1040607661042223
2006	2.0450392537340853
2007	2.0647736413366222
2008	1.8647935347848785
2009	2.0625983556408323
2010	2.449188014131203
2011	2.6436240335061276
2012	2.903603256521707
2013	3.073600045848801