Year	% of total labor force (national estimate)
1975	6
1977	5.88
1979	6.16
1981	7.92
1983	11.851
1985	10.48
1987	9.898
1988	9.369
1989	8.704
1990	7.671
1991	7.285
1992	5.555
1993	6.287
1994	7.159
1995	7.158
1996	6.421
1997	5.511
1998	4.394
1999	3.623
2000	2.725
2001	2.119
2002	2.554
2003	3.593
2004	4.646
2005	5.873
2006	5.007
2007	4.153
2008	3.658
2009	4.352
2010	4.991
2011	4.977
2012	5.821
2013	7.241
2014	7.419
2015	6.872
2016	6.007
2017	4.837
2018	3.832
2019	3.379
2020	3.82
2021	4.209
2022	3.526
2023	3.537