Year	2017 PPP (% of population)
1990	54.7
1991	56.2
1992	57.1
1993	58.2
1994	58.5
1995	58.1
1996	57.4
1997	57
1998	56.8
1999	56.4
2000	56
2001	55
2002	54.4
2003	53.2
2004	50.4
2005	48.7
2006	47.2
2007	46
2008	44.5
2009	43.9
2010	42.1
2011	41
2012	39.8
2013	38.9
2014	38.1
2015	38.2
2016	38
2017	37.5
2018	36.9
2019	36.7