Year	Percent
1973-01-01	3.7276300000000004
1974-01-01	3.3651000000000000
1975-01-01	2.9350200000000000
1976-01-01	2.3078700000000000
1977-01-01	1.9884900000000000
1978-01-01	2.1387900000000000
1979-01-01	2.4589400000000000
1980-01-01	2.7722599999999997
1981-01-01	2.5503400000000003
1982-01-01	2.5503400000000003
1983-01-01	2.5503400000000003
1984-01-01	2.5503400000000003
1985-01-01	2.5503400000000003
1986-01-01	2.5503400000000003
1987-01-01	2.5503400000000003
1988-01-01	2.5503400000000003
1989-01-01	2.5503400000000003
1990-01-01	2.5503400000000003
1991-01-01	2.5503400000000003
1992-01-01	2.5503400000000003
1993-01-01	2.5503400000000003
1994-01-01	2.5503400000000003
1995-01-01	2.5503400000000003
1996-01-01	2.5503400000000003
1997-01-01	2.5503400000000003
1998-01-01	2.5503400000000003
1999-01-01	2.5503400000000003
2000-01-01	2.5503400000000003
2001-01-01	2.5503400000000003
2002-01-01	2.5503400000000003
2003-01-01	2.5503400000000003
2004-01-01	2.5503400000000003
2005-01-01	2.5503400000000003
2006-01-01	4.9890700000000000
2007-01-01	6.0040500000000000
2008-01-01	9.0736800000000000
2009-01-01	9.3265700000000000
2010-01-01	10.0871000000000000
2011-01-01	7.4642700000000000
2012-01-01	4.0742600000000000
2013-01-01	3.9917800000000003
2014-01-01	3.8261500000000000
2015-01-01	3.6008800000000000
2016-01-01	3.4865500000000000