Year	2011 PPP (% of population)
1997	32.8
1998	31.6
1999	32.8
2000	30.5
2001	32.8
2002	29.4
2003	27.6
2004	28.4
2005	30.7
2006	26.8
2007	23
2008	19.4
2009	17.1
2010	14.8
2011	13.3
2012	12.2
2013	11.4
2014	10.6
2015	10.3
2016	10
2017	9.8