Year	2017 PPP (% of population)
1981	48
1988	45.3
1990	41
1992	34.4
1994	24.8
1996	19.8
1998	19.1
1999	22.9
2000	23.5
2002	16.4
2004	12.2
2006	8.7
2007	6.7
2008	5.3
2009	4.5
2010	3.9
2011	2.1
2012	2.3
2013	1.8
2014	1.4
2015	0.8
2016	1
2017	0.8
2018	0.9
2019	0.6
2020	0.7
2021	0.6