Year	constant 2011 PPP $ per kg of oil equivalent
1990	10.9904717689062
1991	10.9495894844181
1992	10.7860064434467
1993	11.0135766924475
1994	11.0199442722015
1995	11.1258255169683
1996	10.797149306213
1997	10.6243472220543
1998	10.4105194796247
1999	10.2274170616988
2000	10.6334246929639
2001	10.596349998225
2002	10.6383744736361
2003	10.5857355284587
2004	10.6056802005482
2005	10.6763932763561
2006	10.7265044161823
2007	10.7667040260121
2008	10.7179731631135
2009	11.0662401450744
2010	10.7614906723219
2011	11.0167406046059
2012	10.7621181938491
2013	10.6329989715912
2014	10.3513483783553