Year	Percent
1963-01-01	30.163450000000000
1964-01-01	31.481330000000000
1965-01-01	31.715090000000004
1966-01-01	30.938930000000000
1967-01-01	29.625420000000002
1968-01-01	26.689190000000004
1969-01-01	28.026820000000000
1970-01-01	33.439950000000000
1971-01-01	41.348180000000000
1972-01-01	52.642169999999990
1973-01-01	62.385800000000000
1974-01-01	74.414550000000000
1975-01-01	85.275410000000000
1976-01-01	84.842159999999990
1977-01-01	73.584940000000000
1978-01-01	66.688570000000000
1979-01-01	60.408640000000005
1980-01-01	61.029759999999996
1981-01-01	57.525830000000006
1982-01-01	40.229110000000000
1983-01-01	39.508430000000000
1984-01-01	46.619800000000000
1985-01-01	47.531990000000000
1986-01-01	50.187480000000000
1987-01-01	60.638119999999994
1988-01-01	53.737060000000000
1989-01-01	49.022490000000005
1990-01-01	44.572850000000000
1991-01-01	27.321910000000000
1992-01-01	10.154420000000000
1993-01-01	9.094257000000000
1994-01-01	18.909470000000002
1995-01-01	35.604160000000000
1996-01-01	35.604160000000000
1997-01-01	35.604160000000000
1998-01-01	35.604160000000000
1999-01-01	35.604160000000000
2000-01-01	35.194270000000000
2001-01-01	35.194270000000000
2002-01-01	32.611630000000000
2003-01-01	30.819380000000000
2004-01-01	35.136030000000000
2005-01-01	41.606460000000000
2006-01-01	48.902670000000000
2007-01-01	48.910970000000000
2008-01-01	59.450380000000000
2009-01-01	63.672390000000000
2010-01-01	56.135450000000000
2011-01-01	53.994930000000004
2012-01-01	53.087040000000000
2013-01-01	54.969040000000000
2014-01-01	58.989360000000000