Year	2011 PPP (% of population)
1981	77.5
1984	77.2
1987	76.4
1990	74.6
1993	74.5
1996	71.9
1999	71.3
2002	68.9
2005	65.1
2008	61.3
2010	56.5
2011	52.8
2012	50.8
2013	48.5
2015	44