Year	Percent
1973-01-01	13.178800000000000
1974-01-01	16.045600000000000
1975-01-01	20.473900000000000
1976-01-01	20.142900000000000
1977-01-01	19.550400000000000
1978-01-01	18.938300000000000
1979-01-01	18.649200000000000
1980-01-01	19.057300000000000
1981-01-01	21.623900000000000
1982-01-01	22.815500000000000
1983-01-01	24.597200000000000
1984-01-01	25.287400000000000
1985-01-01	25.142500000000000
1986-01-01	25.142500000000000
1987-01-01	17.611600000000000
1988-01-01	16.423100000000000
1989-01-01	16.423100000000000
1990-01-01	22.543600000000000
1991-01-01	22.373800000000000
1992-01-01	22.631999999999998
1993-01-01	24.006700000000000
1994-01-01	25.984200000000000
1995-01-01	28.531999999999996
1996-01-01	30.967700000000000
1997-01-01	32.066700000000000
1998-01-01	33.903400000000000
1999-01-01	32.537800000000000
2000-01-01	27.924600000000000
2001-01-01	29.106100000000000
2002-01-01	28.954200000000000
2003-01-01	27.657300000000000
2004-01-01	30.672100000000000
2005-01-01	33.353000000000000
2006-01-01	34.303100000000000
2007-01-01	36.441200000000000
2008-01-01	38.085100000000000
2009-01-01	38.426900000000000
2010-01-01	38.181200000000000
2011-01-01	39.507400000000000
2012-01-01	43.296100000000000
2013-01-01	45.870800000000000
2014-01-01	48.530300000000000
2015-01-01	51.792600000000000
2016-01-01	53.173600000000000