Year	2017 PPP (% of population)
1981	43.8
1982	43.2
1983	42.5
1984	41.1
1985	39.7
1986	38.4
1987	37.5
1988	35.7
1989	38.2
1990	37.9
1991	37.3
1992	36.3
1993	35.6
1994	33.9
1995	32.7
1996	31.1
1997	30.9
1998	31.2
1999	30.3
2000	29.2
2001	28.3
2002	26.9
2003	25.3
2004	23.4
2005	21.6
2006	20.7
2007	19.4
2008	18.6
2009	17.6
2010	15.9
2011	14
2012	13.1
2013	11.6
2014	11.1
2015	10.6
2016	10.4
2017	9.6
2018	8.8
2019	8.9
2020	9.7
2021	9.5
2022	9