Year	Percent
1960-01-01	17.055800000000000
1961-01-01	17.409700000000000
1962-01-01	18.823700000000000
1963-01-01	19.373500000000000
1964-01-01	19.311000000000000
1965-01-01	20.162500000000000
1966-01-01	19.918100000000000
1967-01-01	20.234400000000000
1968-01-01	20.640400000000000
1969-01-01	21.531400000000000
1970-01-01	19.204900000000000
1971-01-01	20.451400000000000
1972-01-01	20.597600000000000
1973-01-01	20.126300000000000
1974-01-01	19.267200000000000
1975-01-01	19.577900000000000
1976-01-01	21.900200000000000
1977-01-01	21.359000000000000
1978-01-01	19.815800000000000
1979-01-01	20.583100000000000
1980-01-01	20.523000000000003
1981-01-01	21.643900000000000
1982-01-01	20.233200000000000
1983-01-01	18.610000000000000
1984-01-01	18.333600000000000
1985-01-01	17.003500000000000
1986-01-01	16.464200000000000
1987-01-01	13.695900000000000
1988-01-01	10.209000000000000
1989-01-01	8.590270000000000
1990-01-01	13.239400000000000
1991-01-01	17.368900000000000
1992-01-01	20.057100000000000
1993-01-01	19.475700000000000
1994-01-01	20.079900000000000
1995-01-01	20.796999999999997
1996-01-01	19.388800000000000
1997-01-01	22.120500000000000
1998-01-01	24.153300000000000
1999-01-01	23.670000000000000
2000-01-01	20.993300000000000
2001-01-01	20.058500000000000
2002-01-01	20.143900000000000
2003-01-01	20.267500000000000
2004-01-01	19.913600000000000
2005-01-01	20.191800000000000
2006-01-01	19.890500000000000
2007-01-01	20.672500000000000
2008-01-01	21.444300000000000
2009-01-01	24.072300000000000
2010-01-01	24.686400000000000
2011-01-01	24.938500000000000
2012-01-01	25.664800000000000
2013-01-01	26.924300000000000
2014-01-01	27.558300000000000
2015-01-01	28.756900000000000
2016-01-01	29.467500000000000