Year	Percent of total labor force
2004	2.5
2005	2.3
2006	3.2
2007	3.7
2008	4
2009	4
2010	3.3
2011	3.1
2012	3.2
2013	3.2
2014	3.2
2015	3.2
2016	3.2
2017	3.2
2018	3.2
2019	3.2
2020	3.2
2021	3.2
2022	3.2
2023	3.2
2024	3.2