Year	% of total labor force (national estimate)
1976	9.86
1977	12.45
1978	13.29
1979	9.45
1980	8.98
1981	7.23
1982	8.39
1983	9.06
1984	17.02
1985	18.85
1986	17.88
1987	17.94
1988	17.57
1989	14.06
1990	8.16
1991	7.52
1992	22.94
1993	24.54
1994	22.98
1995	19.66
1996	14.71
1997	14.61
1998	12.4
1999	10.61
2000	9.35
2001	9.85
2002	10.32
2003	11
2009	10.02
2010	10.69
2013	11.55
2014	12.17
2015	9.803
2016	8.247
2017	8.622
2018	8.322
2019	8.413