Year	2011 PPP (% of population)
1981	74.4
1984	74.6
1987	73
1990	73.7
1993	73.7
1996	71.4
1999	69.7
2002	62.6
2005	54.3
2008	45.4
2010	40.5
2011	37.4
2012	34.2
2013	29.5
2015	24.3