Year	Percent
1960-01-01	1.945765183555640
1961-01-01	3.542256990654650
1962-01-01	4.381780853635240
1963-01-01	2.708775284963620
1964-01-01	3.868574795244530
1965-01-01	4.930906480426440
1966-01-01	2.054817809661350
1967-01-01	3.974672000818070
1968-01-01	2.764860589082920
1969-01-01	3.080397266912190
1970-01-01	4.372834991446710
1971-01-01	4.704264648635650
1972-01-01	6.355134986979420
1973-01-01	7.531080649520160
1974-01-01	9.521793790693590
1975-01-01	8.445252782722890
1976-01-01	7.318688995096580
1977-01-01	5.494609538823420
1978-01-01	3.574325327260010
1979-01-01	3.707403332520800
1980-01-01	6.328320875963700
1981-01-01	6.803038618477460
1982-01-01	5.436023633574800
1983-01-01	3.339173356803990
1984-01-01	5.663187492601400
1985-01-01	3.189511633610090
1986-01-01	1.705446657908660
1987-01-01	1.401952938467370
1988-01-01	1.915720920232490
1989-01-01	2.568343846894670
1990-01-01	3.261873123068230
1991-01-01	3.337428845482120
1992-01-01	4.020845590572120
1993-01-01	3.631785594525430
1994-01-01	2.953403909761250
1995-01-01	2.243366680540290
1996-01-01	1.860973769018420
1997-01-01	1.305983072374970
1998-01-01	0.922465840847906
1999-01-01	0.568990766899814
2000-01-01	2.344864555425660
2001-01-01	2.649999222850550
2002-01-01	1.810359538713190
2003-01-01	1.355556733198260
2004-01-01	2.061203540017780
2005-01-01	2.299138822221460
2006-01-01	1.441546961883790
2007-01-01	2.168555998240370
2008-01-01	3.215950229534910
2009-01-01	0.506308350120954
2010-01-01	1.813536280336810
2011-01-01	3.286581973655120
2012-01-01	2.485673528600680
2013-01-01	2.000158911571960
2014-01-01	1.605804145497510
2015-01-01	0.896565315628228
2016-01-01	0.891592367302732
2017-01-01	2.081268582755210