Year	2017 PPP (% of population)
1981	62.4
1982	61.2
1983	59.8
1984	56.4
1985	53.3
1986	50.2
1987	48
1988	44.1
1989	50.4
1990	49.3
1991	48
1992	46
1993	43.9
1994	40.3
1995	37.8
1996	34.9
1997	35
1998	35.7
1999	33.4
2000	30.9
2001	28.8
2002	25.4
2003	22.5
2004	19.7
2005	16.7
2006	15.9
2007	14.4
2008	13.7
2009	12.2
2010	10.6
2011	8.3
2012	7.1
2013	3.8
2014	3.2
2015	2.6
2016	2.4
2017	2.2
2018	2
2019	1.7
2020	1.6
2021	1.7
2022	1.4