Year	Percent
1977-01-01	11.82027753914890
1978-01-01	9.71603274954341
1981-01-01	13.09885167971350
1982-01-01	10.24026799665880
1983-01-01	10.63857018940150
1984-01-01	10.71944869738370
1985-01-01	8.30147507183768
1986-01-01	8.73355918706676
1987-01-01	8.22580645161291
1988-01-01	9.27204497082204
1989-01-01	11.38713219979580
1990-01-01	11.63475699558180
1991-01-01	13.22426577265070
1992-01-01	10.05611674488410
1993-01-01	11.07355327203890
1994-01-01	13.65178498920440
1995-01-01	12.24955878796600
1996-01-01	9.79430189598023
1997-01-01	7.15468261420502
1998-01-01	7.96521972420802
1999-01-01	5.54439180368748
2000-01-01	4.89062550042567
2001-01-01	5.34550195567140
2002-01-01	5.22336769759457
2003-01-01	5.14044825095995
2004-01-01	4.76979071866842
2005-01-01	5.18126458468109
2006-01-01	6.07271879734298
2007-01-01	6.31049228789322
2008-01-01	10.19060460405110
2009-01-01	4.21077439715842
2010-01-01	4.46275294138450
2011-01-01	5.95444125837764
2012-01-01	4.50963384599508
2013-01-01	4.23623652531453
2014-01-01	3.53436856147326
2015-01-01	2.72064126257004
2016-01-01	2.57815515245079
2017-01-01	3.35108743897026