Year	2011 PPP (% of population)
1981	53.1
1984	49
1987	43.8
1990	44.1
1993	41.6
1996	35.8
1999	34.6
2002	30.7
2005	24.8
2008	21.7
2010	18.8
2011	16.3
2012	15.2
2013	13.3
2015	11.8