Year	2011 PPP (% of population)
1981	39.2
1982	39.1
1983	47.3
1984	46.6
1985	41.5
1986	23.3
1987	33.1
1988	35.8
1989	33.3
1990	38.5
1992	37.2
1993	36.4
1995	26.9
1996	27.3
1997	27.8
1998	25.4
1999	27.3
2001	23.5
2002	22.4
2003	23.5
2004	21.5
2005	19.7
2006	17.1
2007	15.7
2008	13.5
2009	12.5
2011	10.3
2012	8.7
2013	8.2
2014	6.9
2015	8
2016	9.3
2017	9.6