Year	Percent
1960-01-01	19.151400000000000
1961-01-01	18.867600000000000
1962-01-01	18.197700000000000
1963-01-01	18.951300000000000
1964-01-01	19.741700000000000
1965-01-01	19.243200000000000
1966-01-01	18.480800000000000
1967-01-01	20.034900000000000
1968-01-01	20.886800000000000
1969-01-01	19.808800000000000
1970-01-01	18.901200000000000
1971-01-01	21.554200000000000
1972-01-01	24.138800000000000
1973-01-01	24.357900000000000
1974-01-01	24.975200000000000
1975-01-01	25.139900000000000
1976-01-01	27.257500000000000
1977-01-01	29.076800000000000
1978-01-01	32.592500000000000
1979-01-01	36.911800000000000
1980-01-01	39.339400000000000
1981-01-01	41.410700000000000
1982-01-01	41.658000000000000
1983-01-01	38.488600000000000
1984-01-01	37.941900000000000
1985-01-01	36.567800000000000
1986-01-01	34.120600000000000
1987-01-01	35.334300000000000
1988-01-01	36.716000000000000
1989-01-01	38.171400000000000
1990-01-01	38.128100000000000
1991-01-01	30.226100000000000
1992-01-01	29.968600000000000
1993-01-01	29.465100000000000
1994-01-01	28.685400000000000
1995-01-01	26.178200000000000
1996-01-01	27.884100000000000
1997-01-01	21.957200000000000
1998-01-01	13.927100000000000
1999-01-01	14.933500000000000
2000-01-01	16.795500000000000
2001-01-01	18.625700000000000
2002-01-01	19.967600000000000
2003-01-01	20.880300000000000
2004-01-01	21.899800000000000
2005-01-01	22.180400000000000
2006-01-01	22.064900000000000
2007-01-01	22.725300000000000
2008-01-01	24.009200000000000
2009-01-01	25.284800000000000
2010-01-01	24.976700000000000
2011-01-01	24.962200000000000
2012-01-01	24.395300000000000
2013-01-01	25.171300000000000
2014-01-01	25.581100000000000
2015-01-01	26.382500000000000
2016-01-01	27.418000000000003