Year	2011 PPP (%)
1981	27.3
1984	28.7
1987	28.3
1990	29.1
1993	32.9
1996	32.3
1999	31
2002	29.3
2005	24.9
2008	21.5
2010	20.3
2011	19.2
2012	18.2
2013	17.6
2015	17.2