Year 2017 PPP (% of population) 1963 4.7 1964 4.2 1965 3.7 1966 4 1967 3.2 1968 2.7 1969 2.5 1970 3 1971 2.5 1972 2.5 1973 2.2 1974 2.5 1975 2.5 1976 2 1977 2 1978 2.2 1979 1.5 1980 1.5 1981 1.5 1982 2 1983 2 1984 1.7 1985 1.7 1986 1.7 1987 1.5 1988 1.5 1989 1.2 1990 1.5 1991 1.5 1992 1.7 1993 1.7 1994 1.7 1995 1.5 1996 1.5 1997 1.5 1998 1.5 1999 1.5 2000 1.5 2001 1.7 2002 1.7 2003 2 2004 2 2005 1.7 2006 2 2007 1.7 2008 2 2009 1.7 2010 2 2011 2 2012 2 2013 2 2014 2 2015 2.2 2016 2 2017 2 2018 1.7 2019 1.7 2020 1.2 2021 1