Year	Percent
1960-01-01	17.3000000000000000
1961-01-01	16.6000000000000000
1962-01-01	16.4000000000000000
1963-01-01	10.2000000000000000
1964-01-01	9.7500000000000000
1965-01-01	9.7375000000000000
1966-01-01	9.9600000000000000
1967-01-01	12.7417000000000000
1968-01-01	16.1714000000000000
1969-01-01	18.2625000000000000
1970-01-01	14.0394000000000000
1971-01-01	10.2470000000000000
1972-01-01	10.8213000000000000
1973-01-01	12.1209000000000000
1974-01-01	14.8231000000000000
1975-01-01	9.7865700000000000
1976-01-01	8.0860100000000000
1977-01-01	10.9514000000000000
1978-01-01	12.4366000000000000
1979-01-01	13.6359000000000000
1980-01-01	14.5695000000000000
1981-01-01	13.7914000000000000
1982-01-01	10.7087000000000000
1983-01-01	9.0627200000000000
1984-01-01	9.2558000000000000
1985-01-01	7.4341700000000000
1986-01-01	10.4844000000000000
1987-01-01	11.4131000000000000
1988-01-01	11.5560000000000000
1989-01-01	7.0148600000000005
1990-01-01	4.0984500000000000
1991-01-01	4.9796500000000000
1992-01-01	7.5750600000000010
1993-01-01	11.4544000000000000
1994-01-01	13.9044000000000000
1995-01-01	14.8266000000000000
1996-01-01	15.3880000000000000
1997-01-01	17.9823000000000000
1998-01-01	21.0240000000000000
1999-01-01	23.9803000000000000
2000-01-01	24.8561000000000000
2001-01-01	24.3000000000000000
2002-01-01	19.9325000000000000
2003-01-01	19.3140000000000000
2004-01-01	19.5887000000000000
2005-01-01	19.4624000000000000
2006-01-01	18.8718000000000000
2007-01-01	18.3877000000000000
2008-01-01	16.4774000000000000
2009-01-01	17.0655000000000000
2010-01-01	16.1585000000000000
2011-01-01	15.7394000000000000
2012-01-01	16.7482000000000000
2013-01-01	17.2511000000000000
2014-01-01	16.5296000000000000
2015-01-01	17.7954000000000000
2016-01-01	18.7702000000000000