Year	2011 PPP (% of population)
1990	23.9
1997	32.1
1999	38.2
2000	41.4
2001	36.2
2002	38.6
2004	29.2
2005	32.1
2006	28.6
2007	26.4
2008	20.3
2009	18.4
2011	14.1
2012	14.7
2013	12.2
2014	12.3
2015	11.7
2016	12.6
2017	11.8