Year	Percent
1970-01-01	4.7830400000000000
1971-01-01	4.0286700000000000
1972-01-01	3.4545700000000000
1973-01-01	2.8551200000000000
1974-01-01	3.2584600000000000
1975-01-01	4.1137500000000000
1976-01-01	4.1912000000000000
1977-01-01	3.9875300000000005
1978-01-01	4.6489900000000000
1979-01-01	5.4430300000000000
1980-01-01	5.8275200000000000
1981-01-01	6.4612200000000000
1982-01-01	8.8654200000000000
1983-01-01	12.2079000000000000
1984-01-01	14.3141000000000000
1985-01-01	16.5978000000000000
1986-01-01	19.4266000000000000
1987-01-01	19.3669000000000000
1988-01-01	20.5691000000000000
1989-01-01	21.2401000000000000
1990-01-01	16.9659000000000000
1991-01-01	15.6120000000000000
1992-01-01	16.3418000000000000
1993-01-01	18.9954000000000000
1994-01-01	21.2625000000000000
1995-01-01	22.3138000000000000
1996-01-01	20.7059000000000000
1997-01-01	20.7425000000000000
1998-01-01	26.8970000000000000
1999-01-01	26.5624000000000000
2000-01-01	23.4599000000000000
2001-01-01	25.9585000000000000
2002-01-01	27.6127000000000000
2003-01-01	26.8045000000000000
2004-01-01	27.9191000000000000
2005-01-01	30.3099000000000000
2006-01-01	32.2090000000000000
2007-01-01	33.4774000000000000
2008-01-01	33.9480000000000000
2009-01-01	45.5634000000000000
2010-01-01	38.3132000000000000
2011-01-01	32.7761000000000000
2012-01-01	33.6148000000000000
2013-01-01	38.0087000000000000
2014-01-01	42.0183000000000000
2015-01-01	53.5053000000000000
2016-01-01	58.0869000000000000