Year 2017 PPP (% of population) 1997 30 1998 36 1999 48.1 2000 42.6 2001 35.8 2002 30.7 2003 28.9 2004 25.6 2005 22 2006 18.4 2007 13.7 2008 9.4 2009 9 2010 7.2 2011 6.2 2012 5.6 2013 5 2014 4.7 2015 5.5 2016 5.6 2017 5.3 2018 4.9 2019 4.2 2020 4.1