Year 2017 PPP (% of population) 1982 2.7 1983 2.6 1984 2.6 1985 2.5 1986 2.4 1987 2.4 1988 2.3 1989 2.2 1990 2.2 1991 2.3 1992 2.7 1993 3.4 1994 4 1995 3.2 1996 3.6 1997 2.2 1998 2.5 1999 3.5 2000 3.1 2001 2.5 2002 2.2 2003 2.1 2004 1.8 2005 1.6 2006 1.4 2007 1.2 2008 1 2009 0.9 2010 0.9 2011 0.9 2012 0.9 2013 0.9 2014 1.1 2015 1.1 2016 0.9 2017 1 2018 0.8 2019 0.7 2020 0.6 2021 0.5 2022 0.5