Year	2017 PPP (% of population)
1981	30.8
1982	31.5
1983	35.4
1984	35
1985	33.1
1986	26.4
1987	29.8
1988	30.4
1989	29.4
1990	31.3
1991	30.5
1992	30.3
1993	30.5
1994	28.8
1995	28.6
1996	29.7
1997	29.1
1998	28.6
1999	29.1
2000	27.1
2001	26.9
2002	26.4
2003	25.7
2004	24.1
2005	22.5
2006	19.6
2007	18
2008	16.8
2009	16.2
2010	14.7
2011	13.5
2012	12.9
2013	12
2014	11.5
2015	10.8
2016	10.9
2017	10.6
2018	10.4
2019	10.2
2020	9.9
2021	10.5
2022	8.9