Year	Percent
1960-01-01	22.062100000000000
1961-01-01	24.814700000000000
1962-01-01	23.328300000000000
1963-01-01	30.950900000000000
1964-01-01	30.950900000000000
1965-01-01	30.950900000000000
1966-01-01	30.950900000000000
1967-01-01	30.950900000000000
1968-01-01	30.950900000000000
1969-01-01	23.362600000000000
1970-01-01	24.215300000000000
1971-01-01	24.296999999999997
1972-01-01	23.906300000000000
1973-01-01	19.942900000000000
1974-01-01	21.079800000000000
1975-01-01	21.779600000000000
1976-01-01	21.130900000000000
1977-01-01	20.235600000000000
1978-01-01	20.916100000000000
1979-01-01	22.727900000000000
1980-01-01	24.027200000000000
1981-01-01	25.479900000000000
1982-01-01	27.264100000000000
1983-01-01	29.714600000000000
1984-01-01	31.747600000000000
1985-01-01	32.809100000000000
1986-01-01	34.299100000000000
1987-01-01	31.880800000000000
1988-01-01	27.334800000000000
1989-01-01	22.691100000000000
1990-01-01	23.680800000000000
1991-01-01	26.882900000000000
1992-01-01	27.237300000000000
1993-01-01	25.446100000000000
1994-01-01	24.075800000000000
1995-01-01	27.054500000000000
1996-01-01	27.063800000000000
1997-01-01	21.853300000000000
1998-01-01	21.688100000000000
1999-01-01	19.710400000000000
2000-01-01	23.174100000000000
2001-01-01	23.771000000000000
2002-01-01	21.391300000000000
2003-01-01	18.336200000000000
2004-01-01	17.094200000000000
2005-01-01	16.351600000000000
2006-01-01	15.010800000000000
2007-01-01	14.647300000000000
2008-01-01	15.781200000000000
2009-01-01	16.464400000000000
2010-01-01	20.105200000000000
2011-01-01	23.566999999999997
2012-01-01	27.451900000000000
2013-01-01	32.103700000000000
2014-01-01	35.945400000000000
2015-01-01	41.241100000000000
2016-01-01	45.006800000000000