Year	Percent
1979-01-01	3.87633326020342
1980-01-01	3.84223800360344
1981-01-01	3.79032875461909
1982-01-01	4.91579920337154
1983-01-01	7.18331693469897
1984-01-01	6.43055636099121
1985-01-01	5.92540181976572
1986-01-01	5.84213352835152
1987-01-01	5.96121901910155
1988-01-01	5.26137625473353
1989-01-01	4.59713042725291
1990-01-01	5.08473758638365
1991-01-01	7.31112813806664
1992-01-01	8.27730469921851
1993-01-01	8.62133791663196
1994-01-01	7.63829168792093
1995-01-01	6.63774824140923
1996-01-01	6.61306677701548
1997-01-01	6.56406210077874
1998-01-01	6.10071302358167
1999-01-01	5.45810109010976
2000-01-01	5.04582499774412
2001-01-01	5.30364323141360
2002-01-01	5.03990629380731
2003-01-01	4.71317850747093
2004-01-01	4.14044771815049
2005-01-01	3.86288000288404
2006-01-01	3.69198357336788
2007-01-01	3.38711448408909
2008-01-01	3.36499911291786
2009-01-01	4.53509963337687
2010-01-01	4.04376761329396
2011-01-01	3.93670798716880
2012-01-01	4.05311633318182
2013-01-01	4.55585267044975
2014-01-01	4.84165276914446
2015-01-01	4.87177007123671
2016-01-01	4.50167539461868
2017-01-01	4.41216867274700