Year	2017 PPP (%)
1981	67
1982	66.6
1983	65.8
1984	65.2
1985	64.6
1986	64.1
1987	63.9
1988	63.4
1989	63.2
1990	63
1991	62.5
1992	61.7
1993	61.4
1994	60.6
1995	60.2
1996	59.5
2002	58.3
2003	57.5
2004	56.6
2005	55.7
2006	54.9
2007	54
2008	53.4
2009	52.7
2010	50.7
2011	48.2
2012	47
2013	46.3
2014	45.8
2015	45.1
2016	44.5
2017	41.9
2018	38.8
2019	36.9
2020	38.7
2021	37.3
2022	35.2