Year	2011 PPP (% of population)
1997	53.6
1998	53.2
1999	53.5
2000	52.5
2001	55
2002	50.4
2003	49.8
2004	49.7
2005	52.1
2006	46.4
2007	41.1
2008	37.4
2009	35.3
2010	31.2
2011	29.3
2012	26.7
2013	26
2014	25.1
2015	24.2
2016	24.3
2017	23.9