Year	2011 PPP (% of population)
1997	74.6
1998	83.1
1999	88.1
2000	90.3
2001	85.2
2002	75.9
2003	68.3
2004	68.9
2005	74.3
2006	40.4
2007	31.5
2008	32.8
2009	31.5
2010	28.9
2011	25.6
2012	24.6
2013	19.6
2014	18.3
2015	16.1
2016	16.4
2017	16.3