Year	Percent of total labor force
1980	13.623
1981	13.623
1982	13.623
1983	13.623
1984	13.623
1985	13.623
1986	13.623
1987	13.623
1988	13.623
1989	15.1
1990	15.878
1991	16.764
1992	15.564
1993	14.944
1994	14.645
1995	14.352
1996	14.065
1997	14.419
1998	14.419
1999	14.419
2000	14.4
2001	15.73
2002	17.63
2003	16.36
2004	16.12
2005	16.47
2006	16.65
2007	15.852
2008	15.712
2009	15.095
2010	14.628
2011	14.127
2012	13.59
2013	13.525
2014	13.472
2015	13.433
2016	13.416
2017	13.472