Year	2017 PPP (%)
1993	37.7
1994	38.6
1995	38.9
1996	38.5
1997	38
1998	37.4
1999	37.5
2001	35
2002	34.5
2003	33.6
2004	31.5
2005	30.3
2006	29.3
2007	28.1
2008	27.2
2009	26.8
2010	25.6
2011	25.1
2012	24.7
2013	24.2
2014	23.8
2015	24.8
2016	25
2017	24.9
2018	24.8