Year	Percent
1965-01-01	3.3707300000000004
1966-01-01	3.7797500000000000
1967-01-01	4.1176699999999995
1968-01-01	4.6862000000000000
1969-01-01	5.7487600000000000
1970-01-01	5.8795000000000000
1971-01-01	6.1045200000000000
1972-01-01	6.7859600000000000
1973-01-01	6.2293600000000000
1974-01-01	7.2136700000000000
1975-01-01	9.3059200000000000
1976-01-01	8.5978300000000000
1977-01-01	8.1977400000000000
1978-01-01	8.8746900000000000
1979-01-01	10.1699000000000000
1980-01-01	17.1892000000000000
1981-01-01	27.6905000000000000
1982-01-01	28.0022000000000000
1983-01-01	22.4502000000000000
1984-01-01	23.4715000000000000
1985-01-01	26.6519000000000000
1986-01-01	21.7545000000000000
1987-01-01	13.4055000000000000
1988-01-01	13.6531000000000000
1989-01-01	15.1713000000000000
1990-01-01	15.1309000000000000
1991-01-01	13.6899000000000000
1992-01-01	12.8411000000000000
1993-01-01	11.2175000000000000
1994-01-01	9.4788600000000010
1995-01-01	7.6322300000000000
1996-01-01	6.7717300000000010
1997-01-01	5.9890300000000005
1998-01-01	5.3219100000000000
1999-01-01	5.0197000000000000
2000-01-01	5.0572599999999990
2001-01-01	5.4282500000000000
2002-01-01	5.6753200000000000
2003-01-01	5.4166200000000000
2004-01-01	5.2006100000000000
2005-01-01	4.8218200000000000
2006-01-01	4.4131900000000000
2007-01-01	4.0488000000000000
2008-01-01	4.0086100000000000
2009-01-01	4.1709300000000000
2010-01-01	3.9367900000000002
2011-01-01	3.6587400000000003
2012-01-01	3.5094900000000000
2013-01-01	3.4301600000000000
2014-01-01	3.3469500000000000
2015-01-01	3.1674900000000004
2016-01-01	3.0934600000000000