Year	Percent
1973-01-01	0.21146100000000000
1974-01-01	0.21292300000000000
1975-01-01	0.10602300000000000
1976-01-01	0.12359400000000001
1977-01-01	7.68457000000000000
1978-01-01	9.10939000000000000
1979-01-01	12.78060000000000000
1980-01-01	15.91230000000000000
1981-01-01	19.65580000000000000
1982-01-01	24.07560000000000000
1983-01-01	25.09460000000000000
1984-01-01	24.40420000000000000
1985-01-01	23.25660000000000000
1986-01-01	24.80530000000000000
1987-01-01	26.00290000000000000
1988-01-01	23.61850000000000000
1989-01-01	24.51880000000000000
1990-01-01	23.26120000000000000
1991-01-01	21.25790000000000000
1992-01-01	19.86520000000000000
1993-01-01	19.29260000000000000
1994-01-01	21.70290000000000000
1995-01-01	21.60690000000000000
1996-01-01	19.78280000000000000
1997-01-01	19.78280000000000000
1998-01-01	19.66570000000000000
1999-01-01	18.67690000000000000
2000-01-01	24.40280000000000000
2001-01-01	20.31970000000000000
2002-01-01	21.20170000000000000
2003-01-01	19.38640000000000000
2004-01-01	13.66430000000000000
2005-01-01	11.18700000000000100
2006-01-01	11.74240000000000000
2007-01-01	11.86950000000000000
2008-01-01	11.64010000000000000
2009-01-01	12.15350000000000000
2010-01-01	12.65770000000000000
2011-01-01	13.93120000000000000
2012-01-01	17.17710000000000000
2013-01-01	19.01640000000000000
2014-01-01	19.50620000000000000
2015-01-01	19.59590000000000000
2016-01-01	19.28220000000000000