Year	2011 PPP (% of population)
1987	55.2
1994	60.7
1998	60.8
1999	63.4
2000	72.7
2003	53.3
2004	54.6
2005	46.9
2006	41.2
2007	40.4
2008	38.2
2009	38.2
2010	34.3
2011	30.2
2012	27.5
2013	26.9
2014	23.8
2015	24.7
2016	23.9
2017	23.2