Year	Percent
1986-01-01	33.3038472549427
1987-01-01	33.6569216258702
1988-01-01	35.1557197388617
1989-01-01	36.4024918595263
1990-01-01	36.1512656372822
1991-01-01	36.1870053645229
1992-01-01	36.6504349881419
1993-01-01	36.7096987224588
1994-01-01	35.8963047782866
1995-01-01	35.2699793530422
1996-01-01	34.4060508510663
1997-01-01	34.5400177283395
1998-01-01	34.9650521648297
1999-01-01	34.8858026490429
2000-01-01	34.7695863227655
2001-01-01	34.2134996877861
2002-01-01	33.4891368331916
2003-01-01	33.6975381542808
2004-01-01	33.1024202242328
2005-01-01	32.3229763662530
2006-01-01	31.8177589422501
2007-01-01	31.6170332643993
2008-01-01	31.7102580982900
2009-01-01	32.0601780121823
2010-01-01	32.3263081330990
2011-01-01	32.0585043871176
2012-01-01	32.3588855960488
2013-01-01	32.1869825940961
2014-01-01	31.3306848681462
2015-01-01	31.3131376133529
2016-01-01	30.2139968811086
2017-01-01	29.3263391475732