Year	2017 PPP (% of population)
1981	54.4
1982	54.8
1983	58.2
1984	58
1985	56.5
1986	50
1987	53.3
1988	53.9
1989	53.4
1990	55.3
1991	54.9
1992	55.5
1993	55.4
1994	53.2
1995	53.1
1996	53.9
1997	52.9
1998	52.2
1999	53.2
2000	50.8
2001	50.4
2002	50.3
2003	49.8
2004	48.3
2005	45.7
2006	41.9
2007	40
2008	38
2009	37.6
2010	35.6
2011	33.6
2012	32.3
2013	31.2
2014	30.7
2015	29.2
2016	29
2017	28.4
2018	27.9
2019	27.2
2020	27.6
2021	28.4
2022	25.2