Year	Percent
1960-01-01	2.5197500000000000
1961-01-01	2.7051400000000000
1962-01-01	2.6975900000000000
1963-01-01	2.7018600000000000
1964-01-01	3.1638900000000003
1965-01-01	3.5711000000000000
1966-01-01	3.7753200000000000
1967-01-01	3.6213000000000000
1968-01-01	3.0998400000000000
1969-01-01	2.9979500000000000
1970-01-01	3.4779699999999996
1971-01-01	4.1434000000000000
1972-01-01	4.8314100000000000
1973-01-01	3.8967400000000003
1974-01-01	3.7975800000000004
1975-01-01	4.4360599999999994
1976-01-01	4.5777800000000010
1977-01-01	5.0338100000000000
1978-01-01	5.3239900000000000
1979-01-01	4.8764100000000000
1980-01-01	5.3903700000000000
1981-01-01	8.8982800000000000
1982-01-01	14.3547000000000000
1983-01-01	18.6231000000000000
1984-01-01	19.9029000000000000
1985-01-01	20.6588000000000000
1986-01-01	18.8041000000000000
1987-01-01	17.4909000000000000
1988-01-01	17.2031000000000000
1989-01-01	16.3651000000000000
1990-01-01	13.1364000000000000
1991-01-01	12.9128000000000000
1992-01-01	14.2251000000000000
1993-01-01	13.1610000000000000
1994-01-01	12.5158000000000000
1995-01-01	11.7939000000000000
1996-01-01	11.9577000000000000
1997-01-01	11.4326000000000000
1998-01-01	9.8657000000000000
1999-01-01	9.1842000000000000
2000-01-01	9.4657500000000000
2001-01-01	10.4326000000000000
2002-01-01	9.9386700000000000
2003-01-01	8.7422700000000000
2004-01-01	8.4672200000000000
2005-01-01	8.5163000000000000
2006-01-01	8.0563300000000000
2007-01-01	7.3260800000000000
2008-01-01	6.7642500000000000
2009-01-01	6.3408600000000000
2010-01-01	5.9448800000000000
2011-01-01	5.3988200000000000
2012-01-01	5.1936500000000000
2013-01-01	5.1444500000000000
2014-01-01	5.0960300000000010
2015-01-01	5.0405700000000000
2016-01-01	5.0467100000000000