Year	% of population
2001	3
2002	2.5
2003	2.5
2004	2.5
2005	2.5
2006	2.5
2007	2.5
2008	2.5
2009	2.5
2010	2.5
2011	2.5
2012	2.5
2013	2.5
2014	2.5
2015	2.5
2016	2.5
2017	2.5
2018	2.8
2019	3.6
2020	4.1
2021	4.8