Year	2011 PPP (% of population)
1981	27.1
1984	31.8
1987	27.3
1990	29
1993	28.2
1996	27.6
1999	27
2002	24.8
2005	21.3
2008	15.7
2010	14.2
2011	13.1
2012	11.9
2013	11.4
2015	10.6