Year	Percent
1973-01-01	14.1797000000000000
1974-01-01	13.5471000000000000
1975-01-01	15.1743000000000000
1976-01-01	18.2611000000000000
1977-01-01	20.7343000000000000
1978-01-01	20.7343000000000000
1979-01-01	17.5979000000000000
1980-01-01	13.7171000000000000
1981-01-01	18.6483000000000000
1982-01-01	26.1222000000000000
1983-01-01	34.9116000000000000
1984-01-01	34.9116000000000000
1985-01-01	34.9116000000000000
1986-01-01	34.9116000000000000
1987-01-01	34.9116000000000000
1988-01-01	34.9116000000000000
1989-01-01	24.4472000000000000
1990-01-01	24.3375000000000000
1991-01-01	24.3597000000000000
1992-01-01	23.9627000000000000
1993-01-01	18.3768000000000000
1994-01-01	11.5903000000000000
1995-01-01	11.7559000000000000
1996-01-01	10.7654000000000000
1997-01-01	9.9557100000000000
1998-01-01	12.8606000000000000
1999-01-01	11.9511000000000000
2000-01-01	7.2153800000000010
2001-01-01	6.4746100000000000
2002-01-01	5.0459400000000000
2003-01-01	4.5575900000000000
2004-01-01	4.1363800000000000
2005-01-01	3.1489999999999996
2006-01-01	2.4319300000000000
2007-01-01	2.8726400000000000
2008-01-01	3.3029900000000003
2009-01-01	5.1137600000000000
2010-01-01	4.8615600000000000
2011-01-01	5.8302800000000000
2012-01-01	8.4205100000000000
2013-01-01	10.9156000000000000
2014-01-01	13.0183000000000000
2015-01-01	22.1439000000000000