Year	2017 PPP (%)
1981	40
1988	37.7
1990	34.8
1992	30
1994	24.3
1996	20.9
1998	20.2
1999	22.9
2000	23.2
2002	18.1
2004	14.9
2006	11.7
2007	10.3
2008	9.3
2009	8.2
2010	7.2
2011	5.3
2012	5.4
2013	4.5
2014	4.2
2015	2.8
2016	3.2
2017	3.1
2018	3.3
2019	2.5
2020	2.6
2021	2.4