Year	Percent
1975-01-01	2.8056799999999997
1976-01-01	1.8892400000000003
1977-01-01	2.5240000000000000
1978-01-01	3.6243700000000000
1979-01-01	3.3885199999999998
1980-01-01	3.3755900000000003
1981-01-01	3.0967000000000000
1982-01-01	2.9547300000000000
1983-01-01	2.8107200000000000
1984-01-01	2.6357900000000000
1985-01-01	4.8124400000000005
1986-01-01	3.6949600000000000
1987-01-01	4.2176599999999995
1988-01-01	3.3759300000000003
1989-01-01	3.4812300000000005
1990-01-01	3.9866300000000003
1991-01-01	3.4144600000000000
1992-01-01	4.1174200000000000
1993-01-01	4.4572199999999995
1994-01-01	4.9565199999999990
1995-01-01	4.1424000000000000
1996-01-01	3.9821199999999997
1997-01-01	3.4008599999999998
1998-01-01	2.8922100000000000
1999-01-01	2.5093600000000000
2000-01-01	2.4766700000000000
2001-01-01	2.5442900000000000
2002-01-01	3.5388800000000002
2003-01-01	3.2698800000000000
2004-01-01	2.8554400000000000
2005-01-01	2.8372300000000000
2006-01-01	3.0702599999999998
2007-01-01	4.2221199999999990
2008-01-01	4.4200500000000000
2009-01-01	4.4567300000000000
2010-01-01	4.4269700000000000
2011-01-01	6.0417700000000000
2012-01-01	6.6501700000000000
2013-01-01	6.7528399999999990
2014-01-01	6.3959000000000000
2015-01-01	7.0248899999999990
2016-01-01	6.6749600000000004
2017-01-01	6.8019899999999990