Year	Percent
1979-01-01	48.1945068488112
1980-01-01	47.0279458104224
1981-01-01	46.3663606591784
1982-01-01	45.9998127370744
1983-01-01	46.1077114202447
1984-01-01	44.7010986395803
1985-01-01	42.7454395429805
1986-01-01	39.5787952948383
1987-01-01	38.4440392098136
1988-01-01	36.6661632094099
1989-01-01	34.7751753722709
1990-01-01	33.2161843670399
1991-01-01	32.9425745500329
1992-01-01	32.7168047532754
1993-01-01	32.8666780934445
1994-01-01	32.2618086205442
1995-01-01	30.9904518909420
1996-01-01	30.9701799335047
1997-01-01	30.6830597474520
1998-01-01	30.6842664290581
1999-01-01	30.6215692130658
2000-01-01	29.5399658437096
2001-01-01	28.8828389622338
2002-01-01	28.4378459624080
2003-01-01	27.5083355695207
2004-01-01	28.1415473749903
2005-01-01	26.3237591225281
2006-01-01	25.7883503875627
2007-01-01	25.2152518724758
2008-01-01	24.6216256831016
2009-01-01	24.4505074569404
2010-01-01	24.8550775363917
2011-01-01	24.3645754340166
2012-01-01	24.4347985656958
2013-01-01	24.1975940575016
2014-01-01	24.1300940338136
2015-01-01	23.4234813911029
2016-01-01	23.1252351102793
2017-01-01	22.3136870662179