Year	2011 PPP (% of population)
1981	4.1
1984	3.8
1987	3.2
1990	2.9
1993	3.7
1996	4.5
1999	2.5
2002	2.6
2005	2.3
2008	1.8
2010	1.9
2011	1.9
2012	1.9
2013	1.9
2015	1.8