Year	2017 PPP (% of population)
1981	15.4
1982	16.1
1983	18.9
1984	18.5
1985	17.1
1986	12.3
1987	14.9
1988	15.6
1989	15.1
1990	16.3
1991	15.8
1992	15.7
1993	15.6
1994	14.4
1995	14
1996	15.3
1997	15.1
1998	14.8
1999	15.1
2000	13.8
2001	13.5
2002	12.6
2003	12.3
2004	11.3
2005	10.7
2006	8.9
2007	7.7
2008	7
2009	6.7
2010	5.9
2011	5.5
2012	5.1
2013	4.6
2014	4.3
2015	4.1
2016	4.3
2017	4.3
2018	4.2
2019	4.2
2020	3.8
2021	4.5
2022	3.5