Year	Percent
1960-01-01	1.3947399999999999
1961-01-01	2.6847800000000000
1962-01-01	4.6326500000000000
1963-01-01	4.0909100000000000
1964-01-01	3.2029000000000000
1965-01-01	3.2651400000000000
1966-01-01	3.2740299999999998
1967-01-01	4.2211300000000005
1968-01-01	7.0010600000000010
1969-01-01	8.7272699999999990
1970-01-01	11.3123000000000000
1971-01-01	12.6442000000000000
1972-01-01	12.9346000000000000
1973-01-01	17.5284000000000000
1974-01-01	17.3499000000000000
1975-01-01	18.5895000000000000
1976-01-01	20.9585000000000000
1977-01-01	25.2026000000000000
1978-01-01	29.7585000000000000
1979-01-01	25.1964000000000000
1980-01-01	26.3242000000000000
1981-01-01	26.1869999999999980
1982-01-01	27.6482000000000000
1983-01-01	28.0838000000000000
1984-01-01	28.8595000000000000
1985-01-01	29.0034000000000000
1986-01-01	25.9950000000000000
1987-01-01	26.4637000000000000
1988-01-01	27.2488000000000000
1989-01-01	27.3055000000000000
1990-01-01	26.0905000000000000
1991-01-01	26.5378000000000000
1992-01-01	26.5378000000000000
1993-01-01	26.5378000000000000
1994-01-01	26.5378000000000000
1995-01-01	26.5378000000000000
1996-01-01	26.5378000000000000
1997-01-01	26.5378000000000000
1998-01-01	26.5378000000000000
1999-01-01	26.5378000000000000
2000-01-01	26.5378000000000000
2001-01-01	26.5378000000000000
2002-01-01	26.5378000000000000
2003-01-01	26.5378000000000000
2004-01-01	26.5378000000000000
2005-01-01	23.8545000000000000
2006-01-01	17.9699000000000000
2007-01-01	19.0877000000000000
2008-01-01	21.3187000000000000
2009-01-01	23.5469000000000000
2010-01-01	20.9217000000000000
2011-01-01	19.5840000000000000
2012-01-01	20.7972000000000000