Year Percent 1973-01-01 9.51671 1974-01-01 9.50450 1975-01-01 14.99580 1976-01-01 15.08850 1977-01-01 16.61540 1978-01-01 21.34660 1979-01-01 16.87820 1980-01-01 16.87820 1981-01-01 16.87820 1982-01-01 16.87820 1983-01-01 16.87820 1984-01-01 16.87820 1985-01-01 16.87820 1986-01-01 16.87820 1987-01-01 16.87820 1988-01-01 16.87820 1989-01-01 16.87820 1990-01-01 16.87820 1991-01-01 16.87820 1992-01-01 16.87820 1993-01-01 16.87820 1994-01-01 16.87820 1995-01-01 16.87820 1996-01-01 16.87820 1997-01-01 16.87820 1998-01-01 16.87820 1999-01-01 16.87820 2000-01-01 40.59790 2001-01-01 39.58040 2002-01-01 29.94000 2003-01-01 24.61870 2004-01-01 18.04560 2005-01-01 11.83930 2006-01-01 9.68168 2007-01-01 9.27960 2008-01-01 10.71230 2009-01-01 17.98780 2010-01-01 14.60370 2011-01-01 33.84130 2012-01-01 14.12280 2013-01-01 26.44100 2014-01-01 26.44100 2015-01-01 87.35650 2016-01-01 72.93900