Year Percent of total labor force 1980 1.23 1981 1.36 1982 2.14 1983 2.71 1984 2.45 1985 2.91 1986 2.66 1987 1.97 1988 1.69 1989 1.57 1990 1.67 1991 1.51 1992 1.51 1993 1.45 1994 1.56 1995 1.79 1996 2.6 1997 2.72 1998 2.69 1999 2.92 2000 2.99 2001 4.57 2002 5.17 2003 4.99 2004 4.44 2005 4.13 2006 3.91 2007 3.91 2008 4.14 2009 5.85 2010 5.21 2011 4.39 2012 4.24 2013 4.18 2014 3.96 2015 3.78 2016 3.92 2017 3.76 2018 3.76 2019 3.66 2020 3.66 2021 3.66 2022 3.66 2023 3.66 2024 3.66