Year	2017 PPP (%)
1990	41.8
1991	42.8
1992	43.5
1993	44.3
1994	44.7
1995	44.3
1996	43.8
1997	43.5
1998	43.3
1999	43.1
2000	42.9
2001	42.3
2002	41.7
2003	40.8
2004	38.9
2005	37.6
2006	36.4
2007	35.6
2008	34.4
2009	34.1
2010	32.8
2011	32
2012	31.2
2013	30.6
2014	30
2015	30.1
2016	29.9
2017	29.6
2018	29.3
2019	29.2