Year	% of total labor force (national estimate)
1969	2.83
1970	1.89
1971	2.26
1972	2.42
1973	2.45
1974	1.61
1975	2.08
1976	3.75
1977	6.09
1978	7.23
1979	6.2
1980	4.86
1981	5.04
1982	5.28
1983	5.43
1984	5.12
1985	5
1986	5.32
1987	5.07
1988	4.47
1989	3.14
1990	3.069
1991	6.503
1992	11.595
1993	16.201
1994	16.426
1995	17.005
1996	15.572
1997	14.968
1998	13.215
1999	11.693
2000	11.135
2001	10.291
2002	10.423
2003	10.469
2004	10.358
2005	9.602
2006	8.935
2007	6.854
2008	6.369
2009	8.25
2010	8.394
2011	7.781
2012	7.689
2013	8.193
2014	8.663
2015	9.376
2016	8.818
2017	8.64
2018	7.361
2019	6.695
2020	7.759
2021	7.617
2022	6.719
2023	7.151