Year % of population 2001 42.8 2002 37.8 2003 34.3 2004 33.6 2005 33.1 2006 32.7 2007 32.4 2008 33 2009 32.9 2010 32.9 2011 31.9 2012 31.1 2013 29.8 2014 28.4 2015 27.6 2016 27.1 2017 26.1 2018 25 2019 23.8 2020 23.7 2021 22.3