Year % of population 2001 25.7 2002 24.2 2003 20.8 2004 15.8 2005 12.3 2006 9.4 2007 7.1 2008 5.8 2009 3.9 2010 2.8 2011 2.5 2012 2.5 2013 2.5 2014 2.5 2015 2.5 2016 2.5 2017 2.5 2018 2.5 2019 2.5 2020 2.5 2021 2.5