Year	2011 PPP (% of population)
1997	17.9
1998	16.7
1999	17.6
2000	16.3
2001	17.2
2002	15
2003	11.7
2004	13.5
2005	15.3
2006	13.3
2007	11
2008	9
2009	7
2010	5.5
2011	5.2
2012	4.7
2013	4.3
2014	3.7
2015	3.6
2016	3.5
2017	3.4