Year	2011 PPP (% of population)
1981	65.5
1984	64.2
1987	59.6
1990	59.8
1993	56.8
1996	50.8
1999	47.9
2002	40.3
2005	30.7
2008	23.8
2010	19.9
2011	16.8
2012	14.8
2013	10.2
2015	7.4