Year	2011 PPP (% of population)
1990	7.1
1997	19.3
1999	25.3
2000	28.6
2001	22.8
2002	24.7
2004	13.7
2005	19.3
2006	16.4
2007	12.4
2008	11.1
2009	10.5
2011	7.3
2012	8.2
2013	6.9
2014	5.8
2015	6.4
2016	7.1
2017	5.8