Year	2011 PPP (%)
1981	47.4
1984	43
1987	41.4
1990	41.5
1993	41.1
1996	38.8
1999	38.1
2002	35.5
2005	31.8
2008	29.1
2010	26.9
2011	25.3
2012	24.2
2013	22.6
2015	20.9