Year	2017 PPP (% of population)
1993	49
1994	50
1995	50.4
1996	49.8
1997	49.1
1998	48.5
1999	48.3
2001	44.8
2002	44.2
2003	42.8
2004	39.8
2005	38.1
2006	36.9
2007	35.4
2008	34.3
2009	33.7
2010	32
2011	31.4
2012	30.8
2013	30.1
2014	29.5
2015	31.1
2016	31.4
2017	31.1
2018	30.8