Year	PPP $ per kg of oil equivalent
1990	6.115290115071669
1991	6.349784987607955
1992	6.483976513006334
1993	6.723259660767043
1994	6.829458891200359
1995	6.9990245422232205
1996	7.067125620382555
1997	7.284815357131575
1998	7.309802356438677
1999	7.315807680009751
2000	7.67596034067925
2001	7.793210629393779
2002	7.787327229686289
2003	7.9059764612448
2004	8.25634286673801
2005	8.566927932116972
2006	9.01004847778397
2007	9.595651449919048
2008	9.876447166338064
2009	9.889571207258644
2010	10.091934614760355
2011	10.670883214998412
2012	10.917578468490307
2013	11.104562170875559
2014	11.255393896380205