Year	2017 PPP (% of population)
1985	28
1986	28.3
1987	28.8
1988	28
1989	28.3
1990	26.2
1991	27.9
1992	26.2
1993	25.7
1994	25.3
1995	25.5
1996	23.8
1997	22.4
1998	20.3
1999	19.5
2000	18.4
2001	18.6
2003	18.4
2004	17
2005	16.7
2006	16.3
2007	15.9
2008	15.4
2009	13.8
2010	12.6
2011	11.9
2012	11.7
2013	12
2014	12.4
2015	13.1
2016	14.5
2017	15
2018	15.1