Year	2011 PPP (%)
1981	38.1
1984	37.1
1987	35.9
1990	33.9
1993	33.2
1996	30.7
1999	29.7
2002	27.8
2005	25.2
2008	22.9
2010	20.4
2011	18.2
2012	17.2
2013	16
2015	14