Year	Percent
1973-01-01	26.686300000000000
1974-01-01	25.809100000000000
1975-01-01	27.443100000000000
1976-01-01	30.000800000000000
1977-01-01	29.790100000000000
1978-01-01	26.811400000000000
1979-01-01	19.652800000000000
1980-01-01	17.480999999999998
1981-01-01	17.969200000000000
1982-01-01	21.526200000000000
1983-01-01	23.030900000000000
1984-01-01	21.167900000000000
1985-01-01	20.316900000000000
1986-01-01	22.721600000000000
1987-01-01	24.441900000000000
1988-01-01	23.425800000000000
1989-01-01	21.130200000000000
1990-01-01	19.674000000000000
1991-01-01	20.179900000000000
1992-01-01	20.071400000000000
1993-01-01	19.497200000000000
1994-01-01	19.170500000000000
1995-01-01	17.898200000000000
1996-01-01	22.435900000000000
1997-01-01	26.261100000000000
1998-01-01	21.785400000000000
1999-01-01	28.096600000000000
2000-01-01	31.818400000000000
2001-01-01	34.575600000000000
2002-01-01	33.998600000000000
2003-01-01	34.968900000000000
2004-01-01	34.520800000000000
2005-01-01	38.601500000000000
2006-01-01	41.958700000000000
2007-01-01	44.309500000000000
2008-01-01	47.453500000000000
2009-01-01	56.073000000000000
2010-01-01	60.598800000000000
2011-01-01	60.126100000000000
2012-01-01	62.156400000000000
2013-01-01	64.714400000000000
2014-01-01	69.469400000000000
2015-01-01	70.615100000000000
2016-01-01	73.266600000000000