Year	Percent
1960-01-01	17.938100000000000
1961-01-01	17.635400000000000
1962-01-01	17.974500000000000
1963-01-01	18.498900000000000
1964-01-01	18.229100000000000
1965-01-01	17.615000000000000
1966-01-01	19.528700000000000
1967-01-01	19.702800000000000
1968-01-01	19.608200000000000
1969-01-01	21.622700000000000
1970-01-01	15.823000000000000
1971-01-01	18.060700000000000
1972-01-01	19.918800000000000
1973-01-01	19.600500000000000
1974-01-01	19.190600000000000
1975-01-01	20.950800000000000
1976-01-01	22.839300000000000
1977-01-01	23.700100000000000
1978-01-01	28.450000000000000
1979-01-01	27.461800000000000
1980-01-01	24.253600000000000
1981-01-01	26.144800000000000
1982-01-01	29.711900000000000
1983-01-01	38.106400000000000
1984-01-01	40.471900000000000
1985-01-01	42.335600000000000
1986-01-01	43.718400000000000
1987-01-01	44.335600000000000
1988-01-01	44.454600000000000
1989-01-01	43.673500000000000
1990-01-01	40.242200000000000
1991-01-01	39.328600000000000
1992-01-01	37.984700000000000
1993-01-01	36.399700000000000
1994-01-01	36.105500000000000
1995-01-01	36.971600000000000
1996-01-01	38.314500000000000
1997-01-01	43.066900000000000
1998-01-01	45.757100000000000
1999-01-01	43.288999999999994
2000-01-01	38.915900000000000
2001-01-01	40.652800000000000
2002-01-01	42.363800000000000
2003-01-01	33.983700000000000
2004-01-01	30.755300000000000
2005-01-01	31.374900000000000
2006-01-01	33.830999999999996
2007-01-01	32.898700000000000
2008-01-01	29.398900000000000
2009-01-01	52.391500000000000
2010-01-01	52.344700000000000
2011-01-01	43.731400000000000
2012-01-01	47.879200000000000
2013-01-01	50.220900000000000
2014-01-01	53.698500000000000
2015-01-01	62.777100000000000
2016-01-01	68.694200000000000