Year	2011 PPP (% of population)
1998	53.1
2000	77.6
2001	72.8
2002	71.7
2003	69.1
2004	46.7
2005	51.7
2006	39
2007	36
2008	25
2009	21
2010	23.2
2011	21.4
2012	21.6
2013	26.3
2014	19.7
2015	23.4
2016	19.1
2017	19.6