Year	Percent
1981-01-01	12.45289488224910
1982-01-01	10.37476721749370
1983-01-01	11.68363245246230
1984-01-01	11.01552161950560
1985-01-01	7.34485331370136
1986-01-01	8.73355918706676
1987-01-01	9.03867257608165
1988-01-01	10.08403361344550
1989-01-01	10.70897267337340
1990-01-01	10.32675289312450
1991-01-01	13.00697310374280
1992-01-01	10.09896715351760
1993-01-01	10.36115573833210
1994-01-01	11.47700052317000
1995-01-01	10.20904715964820
1996-01-01	9.91002036687498
1997-01-01	7.56223379867265
1998-01-01	9.29598824991836
1999-01-01	6.08886063431494
2000-01-01	4.21531326337137
2001-01-01	4.71489634689610
2002-01-01	3.83082838168467
2003-01-01	5.12899499422415
2004-01-01	5.02342068616283
2005-01-01	6.51685393258431
2006-01-01	6.14552238805966
2007-01-01	7.63235227267791
2008-01-01	11.49070529977690
2009-01-01	4.90494395594705
2010-01-01	5.71860192316579
2011-01-01	7.04308536987611
2012-01-01	5.06770059113205
2013-01-01	5.66920466644127
2014-01-01	5.12734396275528
2015-01-01	4.00047908694748
2016-01-01	3.52448916658203
2017-01-01	3.85443584912304