Year	2017 PPP (%)
1985	26.8
1986	27
1987	27.5
1988	27.1
1989	27.3
1990	25.6
1991	26.7
1992	25.7
1993	25.3
1994	25
1995	25.2
1996	24
1997	23.1
1998	21.4
1999	20.8
2000	19.9
2001	19.9
2003	20.1
2004	18.6
2005	18.4
2006	18.1
2007	17.8
2008	17.4
2009	16.3
2010	15.4
2011	14.8
2012	14.6
2013	14.8
2014	15.1
2015	15.3
2016	16.2
2017	16.6
2018	16.7