Year	Percent
1989-01-01	9.357560000000001
1990-01-01	9.325950000000000
1991-01-01	9.305710000000001
1992-01-01	9.042680000000000
1993-01-01	8.848830000000000
1994-01-01	8.782150000000000
1995-01-01	8.717110000000000
1996-01-01	8.728470000000000
1997-01-01	9.006670000000000
1998-01-01	8.774900000000000
1999-01-01	19.153700000000000
2000-01-01	19.070100000000000
2001-01-01	17.167200000000000
2002-01-01	14.286700000000000
2003-01-01	12.950600000000000
2004-01-01	12.406600000000000
2005-01-01	10.710100000000000
2006-01-01	10.575100000000000
2007-01-01	11.192600000000000
2008-01-01	11.066200000000000
2009-01-01	14.592400000000000
2010-01-01	15.952000000000000
2011-01-01	16.473700000000000
2012-01-01	16.737900000000000
2013-01-01	17.152600000000000
2014-01-01	16.758800000000000
2015-01-01	17.478900000000000
2016-01-01	17.192400000000000
2017-01-01	17.991000000000000