Year % of population 1992 58.1 1997 37.4 2002 28.9 2004 19.5 2006 16 2008 14.5 2010 20.7 2012 17.2 2014 13.5 2016 9.8 2017 7.9 2018 6.7 2019 5.7 2020 4.8