Year	Percent
1980-01-01	11.6903
1981-01-01	14.0019
1982-01-01	15.4540
1983-01-01	11.1635
1984-01-01	23.1329
1985-01-01	26.6827
1986-01-01	29.4670
1987-01-01	28.7041
1988-01-01	26.0986
1989-01-01	25.6679
1990-01-01	27.2383
1991-01-01	22.9132
1992-01-01	23.7568
1993-01-01	25.3701
1994-01-01	30.8678
1995-01-01	30.0478
1996-01-01	30.5458
1997-01-01	26.7156
1998-01-01	24.1989
1999-01-01	23.4970
2000-01-01	19.7010
2001-01-01	19.1326
2002-01-01	18.4471
2003-01-01	18.3887
2004-01-01	15.1661
2005-01-01	13.9394
2006-01-01	11.0785
2007-01-01	11.0325
2008-01-01	13.6501
2009-01-01	20.0585
2010-01-01	21.9101
2011-01-01	26.3701
2012-01-01	34.3786
2013-01-01	33.9303
2014-01-01	37.0051
2015-01-01	30.7952
2016-01-01	27.4574