Year	Percent
1972-01-01	2.39033000000000000
1973-01-01	2.09009000000000000
1974-01-01	2.23917000000000000
1975-01-01	2.01207000000000000
1976-01-01	2.43420999999999980
1977-01-01	3.28675999999999970
1978-01-01	9.33871000000000000
1979-01-01	9.79876000000000100
1980-01-01	8.34401000000000000
1981-01-01	7.16143000000000000
1982-01-01	5.68480000000000000
1983-01-01	5.40198000000000000
1984-01-01	4.68999000000000000
1985-01-01	4.02046999999999950
1986-01-01	3.88359000000000030
1987-01-01	4.26207000000000000
1988-01-01	3.21882000000000000
1989-01-01	2.90616000000000000
1990-01-01	2.11377999999999980
1991-01-01	2.07783000000000000
1992-01-01	1.82782999999999980
1993-01-01	1.34357000000000020
1994-01-01	0.11745499999999999
1995-01-01	0.11489700000000000
1996-01-01	32.82510000000000000
1997-01-01	42.61380000000000000
1998-01-01	36.58590000000000000
1999-01-01	39.03460000000000000
2000-01-01	41.11630000000000000
2001-01-01	44.24090000000000000
2002-01-01	41.24110000000000000
2003-01-01	40.47760000000000000
2004-01-01	42.08250000000000000
2005-01-01	47.47660000000000000
2006-01-01	44.79740000000000000
2007-01-01	42.45160000000000000
2008-01-01	34.93570000000000000
2009-01-01	37.18950000000000000
2010-01-01	33.68240000000000000
2011-01-01	30.74430000000000000
2012-01-01	28.99280000000000000
2013-01-01	28.26370000000000000
2014-01-01	29.27440000000000000
2015-01-01	28.56770000000000000
2016-01-01	31.47440000000000000