Year	2011 PPP (% of population)
1981	52.1
1984	53.5
1987	52.7
1990	53.5
1993	57.6
1996	55.7
1999	52.6
2002	49.3
2005	44.9
2008	40.1
2010	37.2
2011	36.7
2012	35.2
2013	34.3
2015	34.4