Year % of population 2001 4.1 2002 4 2003 3.9 2004 3.9 2005 3.9 2006 4 2007 4 2008 3.9 2009 4.1 2010 4.5 2011 4.8 2012 4.9 2013 5 2014 5.3 2015 5.7 2016 6.1 2017 6.5 2018 6.3 2019 5.9 2020 5.4 2021 5.1