Year	Percent
1975-01-01	2.690090000000000
1976-01-01	5.398800000000000
1977-01-01	8.578600000000000
1978-01-01	9.636289999999999
1979-01-01	9.323260000000001
1980-01-01	10.214600000000000
1981-01-01	12.210400000000000
1982-01-01	14.965100000000000
1983-01-01	16.284600000000000
1984-01-01	15.404400000000000
1985-01-01	17.342000000000000
1986-01-01	17.885500000000000
1987-01-01	19.537700000000000
1988-01-01	24.063700000000000
1989-01-01	27.523800000000000
1990-01-01	27.670000000000000
1991-01-01	24.264500000000000
1992-01-01	23.333700000000000
1993-01-01	22.143000000000000
1994-01-01	25.692500000000000
1995-01-01	31.857200000000000
1996-01-01	33.575900000000000
1997-01-01	37.598800000000000
1998-01-01	39.523100000000000
1999-01-01	37.733800000000000
2000-01-01	37.413700000000000
2001-01-01	37.888900000000000
2002-01-01	38.251800000000000
2003-01-01	40.618900000000000
2004-01-01	39.619300000000000
2005-01-01	41.240700000000000
2006-01-01	45.859500000000000
2007-01-01	47.923800000000000
2008-01-01	51.981500000000000
2009-01-01	47.847000000000000
2010-01-01	40.452300000000000
2011-01-01	34.787200000000000
2012-01-01	31.524700000000000
2013-01-01	30.496300000000000
2014-01-01	30.254500000000000
2015-01-01	31.418900000000000
2016-01-01	34.956400000000000