Year	% of total labor force (national estimate)
1971	2.1
1972	2.7
1973	2.8
1974	3
1975	5.1
1976	6.5
1977	5.67
1978	7.9
1979	6.96
1980	9.1
1981	11.35
1982	13
1983	11.66
1984	11.882
1985	11.321
1986	11.28
1987	11.257
1988	10.128
1989	8.284
1990	7.25
1991	6.984
1992	6.702
1993	8.078
1994	9.645
1995	9.337
1996	9.483
1997	8.95
1998	9.323
1999	8.649
2000	6.586
2001	6.178
2002	6.91
2003	7.68
2004	7.363
2005	8.44
2006	8.246
2007	7.459
2008	6.976
2009	7.908
2010	8.293
2011	7.14
2012	7.542
2013	8.425
2014	8.523
2015	8.482
2016	7.83
2017	7.09
2018	5.941
2019	5.364
2020	5.545
2021	6.248
2022	5.57
2023	5.528