Year	2011 PPP (% of population)
1981	80.5
1984	70.1
1987	59.2
1990	61.3
1993	53.7
1996	40.9
1999	38.5
2002	29.7
2005	18.9
2008	15.3
2010	11.2
2011	8.6
2012	7.2
2013	3.6
2015	2.3