Year	Percent
1960-01-01	11.439800000000000
1961-01-01	12.299500000000000
1962-01-01	13.067400000000000
1963-01-01	10.562999999999999
1964-01-01	8.506490000000000
1965-01-01	10.017100000000000
1966-01-01	12.154100000000000
1967-01-01	15.646500000000000
1968-01-01	20.320300000000000
1969-01-01	25.340900000000000
1970-01-01	28.537200000000000
1971-01-01	29.285700000000000
1972-01-01	30.837300000000000
1973-01-01	30.571700000000000
1974-01-01	29.339000000000002
1975-01-01	27.490300000000000
1976-01-01	25.804400000000000
1977-01-01	27.427800000000000
1978-01-01	27.967200000000000
1979-01-01	27.985000000000000
1980-01-01	29.204600000000000
1981-01-01	29.164600000000000
1982-01-01	31.410999999999998
1983-01-01	31.929200000000000
1984-01-01	30.817700000000000
1985-01-01	30.651900000000000
1986-01-01	30.935200000000000
1987-01-01	30.887200000000000
1988-01-01	31.156800000000000
1989-01-01	32.996900000000000
1990-01-01	32.704300000000000
1991-01-01	32.389400000000000
1992-01-01	33.307900000000000
1993-01-01	33.875600000000000
1994-01-01	33.956300000000000
1995-01-01	33.705600000000000
1996-01-01	34.797100000000000
1997-01-01	35.827000000000000
1998-01-01	44.753500000000000
1999-01-01	50.905800000000000
2000-01-01	58.456500000000000
2001-01-01	64.725300000000000
2002-01-01	65.055000000000000
2003-01-01	66.441300000000000
2004-01-01	63.546000000000010
2005-01-01	61.190600000000000
2006-01-01	60.371000000000000
2007-01-01	57.225400000000000
2008-01-01	58.880100000000000
2009-01-01	63.763900000000000
2010-01-01	65.596400000000000
2011-01-01	70.267500000000000
2012-01-01	72.187300000000000