Year	2011 PPP (% of population)
1981	97.1
1984	96.8
1987	96.1
1990	95.2
1993	93.2
1996	89.3
1999	86.9
2002	79.8
2005	71.6
2008	63.7
2010	56.1
2011	52.3
2012	48.6
2013	42.4
2015	34.8