Year	2017 PPP (%)
1981	39
1982	38.5
1983	37.9
1984	37.4
1985	36.8
1986	36.3
1987	36.2
1988	35.6
1989	35.4
1990	35.1
1991	34.7
1992	33.9
1993	33.8
1994	33.1
1995	32.7
1996	31.8
2002	30.2
2003	29.3
2004	28
2005	27
2006	25.9
2007	24.7
2008	23.9
2009	22.9
2010	21
2011	19.3
2012	18.4
2013	17.8
2014	17.2
2015	16.6
2016	16.2
2017	14.8
2018	13.2
2019	12.9
2020	14.1
2021	13.3
2022	12.4