Year	Hours Per Week
1980	36.5
1981	36.7
1982	36.2
1983	35.9
1984	36
1985	35.8
1986	35.7
1987	35.6
1988	35.6
1989	36.1
1990	35.9
1991	35.9
1992	36.7
1993	36.8
1994	37.4
1995	37.7
1996	37.8
1997	37.8
1998	39.8
1999	40
2000	40.5
2001	39.8
2002	40
2003	39.6
2004	39.2
2005	39.1
2006	39.1
2007	39.3
2008	39.1
2009	39
2010	39
2011	39
2012	36.1
2013	39
2014	36
2015	36
2016	36.33
2017	36