Year	Percent
1975-01-01	33.902300000000000
1976-01-01	28.484200000000000
1977-01-01	29.153900000000000
1978-01-01	31.689800000000000
1979-01-01	34.839000000000000
1980-01-01	35.473900000000000
1981-01-01	32.935200000000000
1982-01-01	36.586900000000000
1983-01-01	41.380600000000000
1984-01-01	39.574300000000000
1985-01-01	38.893200000000000
1986-01-01	37.367100000000000
1987-01-01	37.745500000000000
1988-01-01	38.104600000000000
1989-01-01	41.823300000000000
1990-01-01	41.025400000000000
1991-01-01	40.629900000000000
1992-01-01	42.033700000000000
1993-01-01	44.241100000000000
1994-01-01	46.138200000000000
1995-01-01	48.013000000000005
1996-01-01	53.043000000000000
1997-01-01	55.141400000000000
1998-01-01	55.854100000000000
1999-01-01	59.002700000000000
2000-01-01	64.878400000000000
2001-01-01	64.356400000000000
2002-01-01	64.263300000000000
2003-01-01	62.277600000000000
2004-01-01	58.482600000000000
2005-01-01	60.215300000000000
2006-01-01	59.614100000000000
2007-01-01	63.106000000000000
2008-01-01	65.744400000000000
2009-01-01	67.807400000000000
2010-01-01	65.419100000000000
2011-01-01	62.212300000000000
2012-01-01	62.307500000000000
2013-01-01	61.743600000000000
2014-01-01	61.033400000000000
2015-01-01	58.943100000000000
2016-01-01	58.001800000000000