Year	Percent
1973-01-01	7.2777500000000000
1974-01-01	7.5792500000000000
1975-01-01	7.6770500000000000
1976-01-01	6.3207300000000000
1977-01-01	6.5546600000000000
1978-01-01	11.9974000000000000
1979-01-01	18.0287000000000000
1980-01-01	23.5338000000000000
1981-01-01	30.5935000000000000
1982-01-01	38.5379000000000000
1983-01-01	46.7936000000000000
1984-01-01	52.4920000000000000
1985-01-01	59.7676000000000000
1986-01-01	63.3418000000000000
1987-01-01	65.3317000000000000
1988-01-01	63.5137000000000000
1989-01-01	24.1141000000000000
1990-01-01	3.9326500000000000
1991-01-01	6.5316600000000000
1992-01-01	8.1141200000000000
1993-01-01	7.7482100000000000
1994-01-01	7.2525400000000000
1995-01-01	8.0789300000000000
1996-01-01	8.6221500000000000
1997-01-01	7.9617500000000000
1998-01-01	9.2389600000000000
1999-01-01	8.5849000000000000
2000-01-01	9.2023100000000000
2001-01-01	10.5206000000000000
2002-01-01	10.5672000000000000
2003-01-01	7.3140399999999990
2004-01-01	4.8846300000000005
2005-01-01	4.2951200000000000
2006-01-01	3.5918800000000000
2007-01-01	3.3313900000000003
2008-01-01	4.0047600000000000
2009-01-01	5.0899199999999990
2010-01-01	9.3113600000000000
2011-01-01	13.3283000000000000
2012-01-01	17.8095000000000000
2013-01-01	25.3905000000000000
2014-01-01	33.2487000000000000
2015-01-01	37.7839000000000000
2016-01-01	39.1383000000000000