Year	2011 PPP (% of population)
1981	50.8
1984	52.9
1987	52.8
1990	53.7
1993	54.4
1996	50.7
1999	50.6
2002	48.3
2005	41.7
2008	37.7
2010	35.4
2011	34.2
2012	32.9
2013	31.9
2015	30.8