Year	2011 PPP (%)
1997	26.8
1998	26
1999	26.7
2000	25.4
2001	26.8
2002	24.3
2003	22.5
2004	23.1
2005	24.9
2006	21.8
2007	18.8
2008	16.2
2009	14.6
2010	12.5
2011	11.6
2012	10.6
2013	10
2014	9.4
2015	9.1
2016	9
2017	8.9