Year	% of total labor force (national estimate)
1979	4.8
1980	5.8
1984	7.2
1985	6.9
1986	6.9
1987	6.2
1988	6
1989	5.3
1990	5.5
1991	4.3
1992	4.2
1993	5.1
1994	3.9
1995	3.9
1996	5.1
1997	4.4
1998	4.1
1999	3
2000	2.8
2005	2.11
2006	1.63
2009	4.02
2010	4.37
2011	5.06
2012	5.19
2013	6.08
2014	6.61
2015	7.38
2016	6.45
2017	7.89
2018	7.83
2019	7.54
2020	7.23
2021	6.34
2022	4.91