Year	2011 PPP (% of population)
1979	21
1989	34.4
1991	31.4
1995	24.7
1997	23.3
1998	23.9
1999	21.2
2000	20.2
2001	24.9
2002	21.6
2003	20.7
2004	19.7
2005	18.7
2006	19
2007	16.5
2008	11.8
2009	9.5
2010	10.7
2011	8.6
2012	10
2013	8.1
2014	8.3
2015	6.7
2016	7
2017	6.3